Topping Pre90 Switching op amps?

"Nota bene: The OP was asking about swapping op-amps in the Pre90, not amps to connect to the Pre90."

Thanks kr4. For a second there, I thought that I was losing it, and the funny thing is that the OP didn’t correct them.

@roxy54 

Yes. It was a digression, but interesting nonetheless. My question is on op amps, not amps.

I am running the Topping PRE90 with a VTV Purifi Eval 1 and I agree with your assessment regarding it be the incredibly transparent to the source but can sound thin or brittle. I remedied that with a Jolida SSX tube buffer and it renders the music with more body and tightens the bass. It's the best my system has sounded. Maybe this might be a direction for you rather than swapping opamps.

@rrboogie 

Did the tube buffer reduce the transparency by a noticeable amount? The idea of a tube buffer occurred to me but I thought it would necessarily add some haze given tube equipment generally has higher s/n ratios.

@dbb Surprisingly, it did not not reduce the transparency. I can still hear all of the details. I am using Altec A7 speakers which are over 100db efficient and it added a slight bit to the noise floor but you need to put your ear up to the treble horn. Preamps I had before this were Pass Labs X1, Modwright LS 36.5, Black Ice Audio Fusion F360. All had a higher noise floor. I tried the Topping D70s direct which was excellent on it's own and lead me to the PRE90 which on it's own is dead silent.