Preamp for Parasound A21?

If you are willing to go used, have a look at these: Ayre K5, VTL 2.5, CJ premier 18, BAT 3. You should be happy with any one of them.

Good suggestion, thanks. Would the CJ ET3 or CJ pre-Classic be able to fill the role?

Agm..don't be deceived by the bland utility look of the Wyred4Sound STP-SE. It has 88,000 microfarads of filter capacity. It has 164,560 microfarads of current storage capacity which is one of the highest in the industry of
any Pre-amp at $20K or below. Uses all Dale resistor's. If you like tube's, you will like the Wyred4Sound. Quote from Srajan Ebaen from the 2009 SixMooons review.." Tube Aficionados could be quite shocked to discover that the STP aces the dynamic and timbre expander action one traditionally expects from superior valve units. Compared to most of those I've had through, the STP is quieter and hence more resolved "...For $2K your getting a Pre-amp that has all the performance of Pre-amp's costing up to $15K.

I use the A21 with CJ PV15 and they sound great together. I think both ET3 and Classic will do just fine.

I use an A-21 with a pair of Thiel 3.6s. I initally auditioned a used Audio Research SP-17 that sounded fantastic, but the owner would not lower the price below $2000. I ended up with an SP-16 instead. Not quite as special overall, but still excellent sounding. If you don't need the phono preamp, you could go with a used LS-16 or LS-17 and be within your budget. Good luck.