Recommendation for a highly resolving amp

I am not sure what your budget so I can’t make a recommendation but I do not think you issue is the amplifier. Your pre-amp has a tubed output stage with 6SN7 tubes. What tubes do you have in there ? They can impact your sound significantly. You might try a Pass Labs pre-amp or other solid state linestage as well.

Other things to consider,
speaker set up.  How are your speakers setup compared to your friends?  How is your room setup compared to your friends?
Mine are four feet from the back wall and three feet from the side walls. Mine also sound better when raised higher off the floor.
 I know it might be a pain, but try a speaker swap with your friend.

All the best.

JD

JRDG 625 S2

I don't think the amp is your problem.   I would consider a different pre.

Respectfully, 
Jose

@chungjh If I am not mistaken. You have big speakers in a small room. I believe I recommended in the past you use either acoustic paneling and /or contact Mitch Barnett at

https://accuratesound.ca

to have him measure your room remotely and then have him create Convolution files for your ROON server. So when you stream from ROON to your X1 (before the DAC) your will have the sound optimized for your listening space. This is like using an old time Equalizer but today you do this in computer software.

Some very detailed amps I own or have owned, though I think chasing an amp is not worth it unless you have tamed your room first.

- Benchmark AHB2 (my favorite)
- LSA Voyager 350 GAN (after mods by EVS)
- various Brystons
- CODA #8 (not as detailed but close)

BTW - You replied that you tried Fibre Optic cable. That makes it sound like you tried it and switched to something else. This does not seem correct, because Fibre is so much better than the other connector types. I am not referring to TOSLINK optical cable but Fibre Optical cable.