SET amplifier recommendation

You are not going to get far w/ a SET amp connected to your B&W 805s.  If you want to enjoy the great midrange magic that SET (or SEP) amps can provide, you are going to need a pair of efficient speakers that are happy at 8Ω or 16Ω impedence.  There have been lots of recommendations on Audiogon.  Do a search

B&W, especially the 800 Diamond series, aren't compatible with low output tube amps. They need to be pushed harder in order to shine. Unless if you can find a high current tube amps from say ARC or McIntosh and the likes but those high current tube amps from McIntosh & ARC will be way over your budget of < $3k.

I own a Dynamo MK I, which uses EL34s, but delivers similar power to the MK III using 300B's.   It is not up to driving my 92.5 dB efficient Coincident SVII speakers.  I can't imagine that you are going to be able to appreciate the SET magic driving the B&Ws at 88dB sensitivity.   

The speaker is a problem for almost any SET.

But you've not exhausted all your options. You could also go OTL. Its possible to have many of the advantages of SETs (magical inner detail, amazing midrange) without some of the disadvantages (low power, limited bandwidth) in an OTL. I know people that run that speaker with OTLs, so I know it can work.

+1 shkong78's suggestion.

This is a tough one.  With an SPL of 88dB a 300B is going to be a problem.  You will get 8 to 13w out of most 300B SETs.  Let's assume 10w, you will be getting 94.3dB of volume at 10' from the speaker at full power.  That is not a lot of headroom.

In a mid-size room (20 x 20 is definitely mid-size) you are going to want a bit more power.  

This website will help. 

http://myhometheater.homestead.com/splcalculator.html

Consider your setup and speaker placement.  I find 85dB to be an excellent reference volume and you want about 15dB in headroom to cover dynamics.  Thus, you want to be able to deliver ~100dB in volume.  

Assuming your speakers aren't in the corners of the room and are near the wall (2-4' away) and you listen about 10' from the speakers, you will want at least 30-40

There are not many SETs that deliver that kind of power unless they are parallel SETs which tend to be expensive.  I import Art Audio and have done a lot of studying of SET amps.  The list is not long that will deliver real power.   

If you are looking for a little more in terms of PRAT you could try a different tube.  That ARC uses a 6550 which is popular because it is inexpensive and gives you more traditional tube dynamics than a KTXX but is not in the same league as a SET.  

What you could look for is Push Pull using a different tube type.  

I can only think of one 300B Push Pull from KR and it is not in your price range.  Opera - Consonance make a 2A3 Push Pull at 30w called the 880A.  I believe it should be in your price range.  They no longer have a US Distributor and I have been in touch with them regarding representation.  If you are interested, let me know and I will press them.  

I second that at 88 dB SET is not the best choice.

Although your listening space is not very large, I am not sure whether 300B SET amp can drive B&W 805 with enough authority.

I recommend Line Magnetic 508 or 805 SET amp 48 watt to drive it.


New one is over your budget.

Thus you may want to wait until good used one come out or save some more money.

It’s difficult to imagine how a manufacturer with a direct sales model could have this for a return policy:

"Prepayment by Bank Transfer, Certified Check, or Money Order. NO REFUNDS or EXCHANGES- NO EXCEPTIONS"

... to which I would add "NO SALE!" No product is so special that I would consider buying it under those terms.