which power amp for KEF and Bryston preamp

Coming back to audio recently, I'm trying to decide which budget power amp to match KEF 104.2 and Bryston BP-20 preamp. In particular, among used Bryston 4B/3B and used Classe CA-100, which one would be a better match? Thanks.
Hi Edliu,

I recently purchased a used pair of KEF 104.2 speakers for my son. I loaned him my Bryston 5BST and the pair sounded wonderful together. The Bryston amp provided plenty of power (the KEFs like that) and the sound was very good to excellent. The soundstage was large, wide and deep and the bass was controlled and fast. The KEFs bass goes down to about 40 or 50hz but in their tied together double speaker configuration it needs a good amp to control their motion. The midrange and highs were very musical with no listener fatigue. The Bryston is an excellent match. If you can get a Bryston piece with a chunk of the 20 year warrantee left on it, you would have it all.

Good luck.
I have been using my KEF 104.2's with an Adcom GFA 555II power amp and Adcom GTP 500II tuner-preamp for 15 years. The system sounds so good that I still don't feel any need to modernize. The Adcom tuner-preamp has given me some problems, and I plan to get rid of it soon, but the power amp has been very reliable. There seems to be a good used market for the 555. With the KUBE equalizer, the 104.2's bass goes down below 35 Hz (-6 dB at 20 Hz) and the abundant power of the 555 comes in handy.
I used KEF 104.2 with Bryston 5BST and 3BSST briefly before I upgraded the KEFs to JM Lab Electra line. It souned very good, especially the sound stage and although the KEF spec says 55hz, the bass was very nice tight fast and very musical.

I think a used Bryston 3B/NRG/ST will be a good match for the money.
There is a Bryston 4B-ST currently for sale here on A-gon. I have been using this amp for about 5 years, and have been extremely pleased with it. There is also a Bryston 8B-ST in the "For Sale" listings (it's essentially a 4-channel version of the 3B-ST), which can be used to bi-amp your speakers if you wish.

If your budget allows, you might also consider upgrading the power supply for your BP-20 preamp. The new MPS-2 power supply is quite a significant upgrade to the stock power supply in the BP-20. I recently replaced the MPS-1 power supply (for my Bryston BP-1.5 phono preamp) with the MPS-2, and found that the MPS-2 provided better transient response and a bit more clarity than the older power supply.
I have a late model BP-20P, with the improved MPS-1 power supply and longer input and output jacks. I use it with a 3B-ST amp. Speakers are the Spendor SP 2/2. The roon is 17' X 14' X 8'. The sound quality is great. Solid, natual, and clear. I feel that using pre-amps and power amps from the same company make a lot of sense. They should mate pretty well!!