Have opportunity to buy BHK 300's or Pass Labs 250.8 for my Thiel 3.7's- thoughts??

Thank you everyone.  Believe it or not BOTH deals fell through one of which was as a result of an unreliable seller- but so be it,

If I may, do you have any thoughts about Quicksilver V4 mono's?   I have always wanted to try tubes with the Thiels.   I will probably contact Mike Sanders in the morning.  

@Unsound- I generally do not listen very loud although sometimes I do crank the music up (80db or so would be my guess for an upper limit) and I sit some 10 feet away from the speakers.

^It’s not always about ultimate volume but rather about operating in the realm of the load of the particular speaker.

@pgastone IMO some of the best tube monos for the 3.7s are the VAC Signature 200iQ.http://www.vac-amps.com/productPages/Signature200.html
I don't know if that's within your budget ?

it would be a very far stretch- used single units range around $4k (give or take $200)- and there’s the matter of finding 2 of similar age and tube usage.
I was originally looking to spend some $5k for solid state- i realize tubes would be more but 8 really do not want to go much beyong $6k.

Quicksilvers  V4’s have a very good reputation - i know of several audiogoners that swear by them- and are hand wired for much less (mono’s) but of course the transformers are key.

And FYI
I just spoke to Mike Sanders- it was a pleasure and he in fact discouraged using the V4 with the Thiel 3.7's (which he seemed quite familiar with).   The source impedance of the amp is too high and would not match with the speaker's fairly impedance dips.  

This is something that unsound had been mentioning.

On the other hand he explained that the mono 120's are specifically designed for more difficult loads and should handle the Thiels well.  

One of the problems of course is that this kind of information rarely readily available unless the amplifiers have been reviewed and appropriately tested.

I want to look more into this- very interesting.   I just wonder what kind of output impedance would then be considered a good match- yes obviously the lower the better but that is just a relative comparison.  I would like to know about the matching in more absolute terms.