Amp Basics: Tube Preamp w/Solid State Power Amp.

The wattage of the power amp is more of a matching issue between amp and speakers. The key matching preamp to amp is the output impedence of the preamp and the input impedence of the amp. The general rule of thumb is that the input impedence of the power amp should be 'AT LEAST' 10X's the output impedence of the preamp. I say 'AT LEAST' because the higher the ratio the better, in fact some manufacturers will recommend a 20-30X ratio to be the minimum. In other words, your PrimaLuna Prologue 3 tube preamp has an output impedence of 2800 ohms, which is very high for a preamp. You should look for an amp with an input impedence of AT LEAST 28Kohms. 100K would be better yet.

As for reco's it depends on what type of sound you are looking for. If looking for rich, warm sound, there currently is an older Jeff Rowland Model 1 amp, which has adjustable input impedence of 600 ohms, 20Kohms and 100Kohms. Obviously you would be best to use the 100Kohm setting. It also has selectable gain of 20, 26, 29.5, 32 dB which should help match your preamp even more.
If you're looking for more power and/or a a faster, more transparent amp, there is a Belles 350A Reference for sale with an input impedence of 50Kohm.

Obviously these are only two, there are more amps out there. With your preamp's high output impedence you will just have to be careful that the amp's input impedence is high enough to match. FWIW, impedence mis-match is not lethal, it will just roll off the high's and low's.

Cheers,
John

The only other thing I'd add to John's advice is to be aware of that if you mate a high gain power amp ( a separate issue from power rating ) to a high gain preamp, you can have too little range of effective volume control before things get too loud. It's not a fatal flaw, inline attenuators can ameliorate that with no sonic penalty. The Prima Luna's 12db is pretty middle of the road in the gain department, shouldn't be any cause for concern with the majority of amps you'd pair it with.

If you don't want to worry about matching impedence, you should look for a little device callled a Burson buffer. It would make the output impedence of your preamp look more compatible with say a low input impedence ss amp. Pretty cool.You can google Burson buffer and get the info.

Thanks, lots of help. The information I was looking for.

Do a search for tube preamps, there's been quite a bit of discussion on them.

I run a TAD150sig tube pre into a McCormack DNA1 power amp. This has been a very good combo in many folks systems...including mine. I run power-hungry 4 ohm speakers & the gain-volume control issue hasn't been an issue in my system.

McCormack power amps have a great reputation & can easily be had for 1-2K, depending on the power you need & it's upgrade status. Steve McCormack will do upgrades on the amp if you want..this gives you some upgrade headroom down the road without switching to another amp.

If you're looking ofr an overall primer on audio system basics...Robert Harley has a Guide to High End Audio book that is useful.