Just to clarify, I was looking at the OP's preamp when I made that comment. I feel that's easily the weakest component in the system and would upgrade that first. If the OP found a nice DAC with a volume control that would eliminate the need for the preamp altogether, that should work well too. It would also be fair to point out that the OP's speakers are very revealing and are excellent at pointing out even small changes. I took that into consideration. If you make a mistake, those speakers will make you pay for it. If you get it right, just the opposite.