Looking to buy my DB a pair of headphones for her workroom system - CDX into Meridian amp with an “Olive” Headline+NAPSC as the headphone amp. No changes to the system are envisaged, and no Blootoof, noise cancelling, or whatever needed for the cans. Just a bog standard set of good sounding wired cans.
The Massdrop 6xx is on sale for USD 199. If you don’t know it, it is made by Sennheiser and is virtually the same as the Sennheiser 650. When I did my research years ago, the only difference was the cable length. 4.8* based on 6,459 reviews.
I suggest you decided first whether you closed back headphones are needed. Does it matter it there if there is sound leakage? Will the listener need isolation from other nearby sounds?
Perhaps just offer to buy and let her audition a few. As others have mentioned is isolation and sound leakage a consideration?
SQ aside, comfort is also very important. Grado make great sounding headphones but for me they are very uncomfortable so a non starter for long listening sessions.
You can find them in “open box” sales,.or pre-loved for around the price you mention.
They are very comfortable to wear,.but need a “burn in” period of 150 hours,something that Hifiman also recommends.
Run this “burn in” even if you buy a pair pre-loved,.I did that with mine and they got better.
Also,.there are better options than the original cable,please consider this later as an option.