How much do you want to spend? On the low cost end there is iBasso and on the higher end Head Amp. Both are awesome in their respective brackets and of course the higher priced unit does sound better.
Darn, so tempted to buy. I have listened to some of the Musical Paradise units and they sound very nice at a good price point. Sure hope this further improves the sound quality.
Larry, IMO you need to open the unit up to do the job right. I would take pictures as you open the unit to document the as found condition and I would first put the unit outside and "dust it off" using compressed air. Make sure you do...
kindasonic, the SRGII is IMO a very nice sounding amp. Did you get the PSU1 with it or the switching PSU? If the second make sure the SRGII is grounded using the grounding post on the back of the amp. Good luck.