Seem like you are open minded, Beave has given you some or all of the reasons why you old Arcam "just sounded better".
There are numerous examples and even double blind comparison listening tests that show the way you did your comparison would be very prone to expectation bias and Placebo effects. So your impression from such comparison listening sessions were unreliable, anecdotal at best.
Just one example, food for thought:
I am following this forum from long time but have never written here. So this is my first post. I recently replaced my Arcam AVR390 with Denon X3600 for obvious reasons. I was never satisfied with the Arcam for the two years i owned it. I made a lot of measurements trying to fix the problems i...
www.audiosciencereview.com
This owner of both an Arcam AVR390 and a Denon AVR-X3600H, now he is considering selling the Arcam, may be you can PM him if you are interested in it. The AVR390 is a much newer and higher end version than your AVR250. Now he never said anything about music, but just compare the measured distortions of the Arcam with that of the Denon, before you may say the Arcam would sound better in music. All such subjective impressions really mean little, because the listeners knew which device is playing. I am only quoting this one here as an example.
Another thing, I would rather believe you listening impression were skewed because it was a sighted test, than to think that you actually prefer more distorted sound, though that is not impossible.
I am following this forum from long time but have never written here. So this is my first post. I recently replaced my Arcam AVR390 with Denon X3600 for obvious reasons. I was never satisfied with the Arcam for the two years i owned it. I made a lot of measurements trying to fix the problems i was hearing and never completely achieved what i was looking for ( measuring with REW and calibrating with Dirac). Testing the denon for 1 week and made only 2 measurements with audyssey and 2-3 different curves and i can honestly say after watching the movies i always watch as reference that it is completely insane difference.
The denon is soo much better to the point that am hating arcam for loosing 2 years of my life not listening to my theatre the way it is supposed to sound. I can post numerous REW files with the arcam compared to what I now have with denon and audyssey for evidence if required even seat to seat consistency is almost perfect. As a reference i have 3 subs pre-calibrated with miniDSP and separate amps ( Audiolab 8200m and 8200p) for the main layer of speakers + 4 channel NAD for atmos ceiling. I was about to purchase Arcam AV40 but i am glad i didn’t. I do not miss XLR outs.
I am even wondering whether to sell the AVR390 and disappointing someone else.
I will post more info about why I consider the A-S801 is an AVR based amp, not that it means bad..