ATC 50A or Kudos 606 for low level listening

I’m starting a system from almost scratch.
Have a good source and DAC, ZENmini Mk3/LPS, QUTEST already in my HP rig.

I had a demo of a Sonus Faber Olympics Nova 2 with Pass Labs INT 60. I was so impressed with the INT 60, it easily seen of a Gryphon Diablo 120.

Which surprised me l, as the Diablo 120 is rated very, very highly in most reviews and Internet forums.

I had a ATC SCM50A in a previous life before I had to sell for personal reasons. However I rarely listened at low levels, I usually cranked it up for a full on session.

As I get “mature” in life etc I’m finding myself leaning towards lower listening levels and just relaxing into the music more.

Thats why the Pass INT 60 just talked to me like no other amp ever has. The Class A goodness just flowed and had me be transfixed and at ALL listening levels, whisper levels to balls out rock stadium levels. And at those rock stadium levels it was never hard or uncomfortable, but all the detail, musical flow, soundstage etc was all there.

So my question is really, will the Kudos 606 deliver what I’m after ?

I’m not sure if I go back to the ATC SCM 50A that I’ll have that intoxicating music that the INT 60 provided.

For various reasons I’m not looking at the Sonus Faber Nova 2. It captured the musical flow of the INT 60 very well, just something about it that seemed off to me.

That and it needs to have some area to work in the dealer said. I’m unfortunately locked into a small area that I can give my speakers. About 30cm is all I can spare to the solid brick wall behind them.

That’s why the 606 has my interest.

If it helps, I do a lot of my listening late in the day and for that reason, at low level. The Kudos 606 / NAP 250 combination works well for me at low levels. There are obviously many other options to consider. Is a home demo possible?

My 808’s are very sensitive with a 500 up them. They make music from the point the amp kicks in. Never need to listen past 9 o’clock and depending on the recording that can be way too much. I only had the small ATC’s but they needed some welly to get them going.

I have the 606s running through an Aavik I-280. I absolutely love them and replaced Borresen Z2s with them. They are also the easiest speakers I have ever had to place, 2M apart and about 30cm from the rear wall. The 606s are my end game speakers. Low level is great. The Aavik I-280 is about 300 watts into 8 ohm. The 606s are not very efficient at 84db, I think it
best to try them with the amp if you can. I think they will be fine but better safe than sorry.

Couldn’t get 606’s to work in my room…… ultimately it’s all about room matching and the ATC’s work a treat in my room - worth doing the hard yards and demoing to get the right match for you.


I have never hear ATC speaker so can’t comment on those but I have been using T606s for over three years nd they are excellent at low level listening especially with a NAP 300.

Speakers are a very personal choice and must work in your room, been using Naimfor 40 years with a different speakers over the years in the same room the only speaker that did not work in my room were SBLs.

Not surprising to me at all, as speakers all sound different from one another, even at very elevated price levels, and everyone has their own taste in the sound character of music replay. This was brought home to me many years ago when I did a mammoth audition of 13 speakers, all in the same quite high price bracket*. Considering that they all had received very good reviews, with most being the flagship of their respective manufacturers’ ranges, I was surprised and amazed at how different they all sounded - ten sounded so bad to my ears that I rejected within the first couple of minutes (yet at least one of those is loved even now by a number of forum members). Of all system components, speakers have the greatest effect on the sound character of a system. This is why I strongly advocate finding speakers that you love early on in system building, just ensuring the amp has enough control to make them sound good enough and that the source is half decent, then improve other components later.

The take-away from the above is that you absolutely have to hear for yourself, and only be guided by someone else if you know their taste in sound presentation is the same as yours - but other than that, recommendations for what to try are of course entirely valid.

As for low level listening, the variation in sound character between high and low level playing may vary more with some speakers than others, however always at low levels (though it depends what you mean by low) the frequency extremes, especially at the bass end, will diminish unless boosted to compensate for the ear’s sensitivity roll-off, such as with a “loudness” compensator. Unfortunately an on-off button, so beloved of low/mid-fi systems of the 80s, is very crude, not being related to actual requirements so near correct only at one sound level - though at very low levels that might be better than with no compensation at all. I long for the day when someone introduces a device giving correct (=sound level related) loudness compensation: although inevitably complex to implement, with today’s digital technology I’m sure it would be entirely possible, and done well any minor sound artefacts would be less significant than the negative effect of frequency loss with low level listening.

(*Inflation equates to something like £2.5-£3k today, but there weren’t very many speakers priced significantly higher in those days, and at least some of those speakers if made today would be considerably more - the IMFs I bought then would sit somewhere between the PMC Twentyfive.24 and 26 in equivalent models today, so somewhat in excess of £6k.)


I have ATC SCM11, originally on my main system and now in my bedroom, and they’ve always needed a bit of volume to get the best out of them. Not so my 606.

That was exactly my experience also.

So much so that I built an amp to suit the speakers (and I specifically incorporated design elements into it to cope with the ultrasonic breakthrough from early CD players).

That approach worked really well!

There are a couple of things here:

The Pass amps are excellent at low volume, with the right speakers the low volume listening is outstanding and matched by few others; however, in my experience the low level Class A approach (or high bias current approach) does need the right speakers, and very few reviews mention this, so it tends to be a case of asking on forums such as this then careful auditioning.

As IB says speakers are very much subject to individual taste, probably more so than any other component. Like them I ‘interviewed’ more than 10 different speakers and less than half made it past the first track. (Also including a lot of very well respected speakers like the Mission 770 Freedom - great at ear demolishing levels, but as soon as you turned it down to a sustainable level, they sounded as though they were hidden under a 15tog duvet!)

The other issue is the size of the room, you mention a small area, unfortunately when driving small rooms, it’s very easy to create huge mid-bass resonances due to the dimensions of the room - there are a number of applications and internet sites where you can enter the size of the room and they will calculate where the resonance peaks will occur. REW goes further than this, in that it allows you to position speakers and the listening position and to calculate a theoretical frequency response for the room. It is well worth experimenting with this to test possible setups.

Finally, if it’s impossible to reduce the bass resonance sufficiently, small satellite speakers and a sub with a DSP are the most effective solution. You may need to consider this if you are sensitive to bass boom type issues.

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Thanks for that. I should have been clearer, my room is 8m X 4m the listening space is along the short 4m side.

So I’m OK room size wise for the 606 ?

The ATC50A that I had was along the same wall and was OK.

If need be, I can stretch up to the Pass INT 250, that’s a monster amp apparently and can easily drive almost any speaker out there.

But I’ll loose that Class A bias that the INT 60 has, it stays in Class A up to about 30 watts, the INT 250 only up to 15 watts.

But…., has that massive 250w headroom if needed.

With most speakers, 15WPC isn’t exactly low level listening that’s about 90 to 95dB at the listening position!

With a 2 to 1 length to width ratio, it’s well worthwhile getting a copy of REW (it’s freeware / voluntary contribution software) if only to experiment with speaker and listening position adjustments. This will give a better indication than I ever can of whether the 606 will excite the bass resonance (then again your sensitivity to this effect may be a lot less than mine).

Even if the changes of position are small, it can be useful to know how small changes can affect the sound in the room: smaller rooms can be quite critical for speaker position. Later on if you want to use a microphone, it’s possible to measure the actual response.

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Thanks all for your thoughts.

I’m going to have to revise my budget down.

Now looking at a SN3 and 606 or 505. Along with my existing source of ZENMini mk3/LPSU, Qutest DAC.

Would this be an OK set up ? Or am I up against it balance wise and the 606 really needs a better amp ?

It’s all that I stretch to budget wise.

I did think about the ATC 40A, but I have had that in the past and although it had a lovely midrange, treble etc it was lacking the bass depth that I ultimately wanted / needed.

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Personally, I would put an M Scaler in front of the Qutest. Any decent pair of £5,000+ speakers will highlight the limitations of the Qutest, great value though it is.

I had to do similar with a DAVE…

Best regards, BF

I did think about that BF, and assumed that I might as well trade the QUTEST in on a HTT2 as to get a MSCALER.

Unless you think a QUTEST/MS is better than a bare HTT2 ?

Ah, okay. I haven’t auditioned a TT2, so can’t add much other than to say that either option will be a great help.

I’m running the following
Zenith Mk3
Supercap DR
250 DR
Titan 606
WithchHat Phantom speaker cables

Speakers are 2m apart and 30cm from the wall.

I’m mainly a “background music” man so run at low levels when I’m working but I do crank them up at the weekends.

System sounds sublime and short of a lottery win I won’t be changing the 606’s.

Next steps are as follows:

  1. Add another 250 with new Kudos crossover (when launched)
  2. Trial Kudos KS-1 speaker cables
  3. Swap SN3 for a 252

That will be my end-game NAIM / speaker setup achieved but I may dabble with MScaler or a TT2.

I’d suggest a home demo but appreciate this isn’t easy at times.

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I think I’ll have to revise again….

Just found out the prices are going up in my country for all Kudos.

How close to the 606 is the 505 ?
Unfortunately I can’t demo the 505.

When I demoed I didn’t like the 505…too bright I thought, much preferred the 606…worked for me…

I had the 505s for 2 years. Loved them but the 606s just provide a little deeper bass. Similar sound signature in my system/home. Both are/were incredibly well balanced, detailed and great at low and high volume. Soundstage is excellent as well, with placement of both speakers very simple. They easily fit in my living environment. The tweeters presentation is something I really appreciate, detailed, crystal clear, smooth with no hint of brightness for me.