Hi
I had the same problem with my used 552.
The 252 I owned from new done things slightly better.
I was very surprised given the price difference.
Once I serviced the 552 then the differences were easily heard.
552 is an excellent pre amp.
Mark
1 Like
My 552 is a 2007 (dr’d in 2013 but not serviced) and its sounding the best I’ve ever heard it. I really don’t think yours needs servicing as such but may have a slight problem with it, maybe a component playing up.
Thanks Nigel. I have done quite a bit of faffing with the cable dressing and whilst I can make matters worse, I’m not getting any real improvement. Your point re the mains block may warrant some exploration. Similarly with the plug order which has a very subtle effect but nothing dramatic. I don’t have any else plugged in.
At present the block is a lowly Matrix 2 which I am in no doubt going to need to replace soon. The appearance of the Chord blocks appears to have released some MusicWorks G3 blocks onto the used market, so I’ll dip my toes into that. (Re-selling if it doesn’t work out)
The level of extra detail with the 252 is very clearly evident through the current block though and whilst the 552 doesn’t sound dull in the greater scheme of things it lacks the level of information being presented by the. 252.
I know the 552 has been in constant daily use since 2011, so a service might be the solution. I had already budgeted for that and getting it done whilst I still have the 252 to slot back in would make sense so I am erring in that direction.
I used to use Matrix 2 blocks but have changed to G3, and while there was an improvement, that does not explain the lack of detail from the 552.
If your 552 has been in constant daily use since 2011 then the need for a service is probably the issue. I believe my 552 was lightly used by its previous single owner as he travelled quite a bit. To be fair it would also probably benefit from a service (and I will get it DR’d at the same time) but it is still sounding wonderful.
Good luck.
That’s helpful Mark. I am likely to explore the servicing route. Sounds like a similar situation and one which potentially provides a plausible explanation for the current issue. It’s good to know someone else has explored the possibility successfully.
I think anyone listening to the 552 as it stands would say that it is very good. There is no doubt about that. At present though, if asked which was the “ better” preamp in a blind test I am pretty sure most people would pick my current 252, which clearly isn’t the case. I’d really like to get the 552 working to it’s obvious potential and a service will hopefully achieve that.
3 Likes
Thanks for the reply Stu. Mine, like yours was a comparative bargain, given some of the recent sales prices achieved, so I’m not adverse to the service cost to enhance the performance 
So the power supply was sent off to be DRed and the 552 just left?
That 552 is going to want a service by now just as mine did
1 Like
Hi Dunc, yes. The DR update was done in 2013, as the head unit was only 2 years old at that stage. The only work done on the PS was the DR upgrade. The two units are now 11 years old so seems reasonable that it will benefit from a service.
Some years ago I compared 200DR vs. 250DR at home and not really hearing a meaningful difference, which left the dealer quite surprised.
When investigating the setup we found that the 200 power cord was pluged into the same mains block as the rest of the system, while the 250 power cord was pluged into a different block.
When pluging both amps into the same mains block, suddenly the differences between these two amps was immediately aparent and the price difference well justified for me.
My conclusion was that mains, earth and placement have a huge impact on such comparisons.
How did you setup your comparison? Did you remove the 252/SC and place the 552/PS in the same place?
Hi yes including Powerlines and the same interconnects. Obviously the Burndy cables are amp specific so that is the only other real variable. I have also experimented with different plug orders etc as well as cable dressing.
Hi Steve
Mine was a touch older but it really needed a service as right before it was boxed up one channel had started to really go off.
But the problem is the sound deteriorates over time and you just dont notice how much its gone off till you try it against a newer one, etc or like mine starts to fail.
I would get the 552 serviced asap, then go through the pain off burn in, but out the box for the first few hours you should hear a nice difference before it starts to go up and down as it burns in
Prepared for that pain in the pursuit of the greater good I think. 
1 Like
Get a Hydra. Cheap, and made a decent change to my rig.
1 Like
I’ve just changed my 2018 252 & 2019 supercap for a 2013 552DR - Unserviced. Even from cold there was more detail and tighter & deeper bass.
I’d double check all the cabling is correct then look at positioning on whatever racking you use - keep the preamp away from power supplies as much as you can.
Thanks! What is a Hydra and what would it do?
Try google, or search on the forum. Works well for a lot on here.
Well googling Hydra leads to results that I rather not want to have around me 
But seriously: There surely is a reasoning you suggest a hydra for my system? Maybe you would be kind enough to point me into a direction?
Its called a Grahams Hydra their website will tell you all about it.
I use a three headed one on my setup a neat and simple way to power my Naim equipment.
1 Like
I have not read all this thread but really in a sane world if your existing pre sounds better, just stick with it - why are you trying to convince yourself that you want this 552?
.sjb
7 Likes
Yup. I have a 4 way one… 