I recommend keeping the Mark Levinson 23.5. Seriously you would have to spend lots more money to find an amp anywhere close to this one. Also, the next upgrade in my opinion would be to obtain an Audio Research REF 3 pre-amp over your SP-11. I had an SP-11 and compared it with the Boulder top of the line pre amp, REF 3, SP16, SP17 and Krell's pre-amp. The REF 3 beat them all except the Boulder and it was very close. When you get to that level, things are in small increments, not large ones. But, over the SP-11, even my retubed SP11, there was enough of a difference, not very large, but enough that I sold my SP-11 and bought the REF 3. Really I wanted the remote ability and nothing was better than my SP-11 but the REF 3 for the money. So, keep the 23.5. Everyone I know that had one and sold it regretted selling it later. I finaly got one and now I have to sell either my Audio Research VTM 120 monoblocks (retubed) or my ML3. But, something has to go. The 23.5 sounds wonderful.