Tube amp with gain controls..any suggestions

You should be able to do it (with less than optimum results IMHO) by getting a ss amp with more input sensitivity than the tubed amp and then putting an attenuator between the preamp and the ss amp. Using this attenuator you could come close to matching their output. You would then use the attenuator on the preamp to control both amps. BTW, if your preamp has two outputs be sure you know how they are configured. It ain't all that straight forward (I found out the hard way). If you can't find out, then take the signal out of the preamp using a 'Y' connector.

Hope that helps a bit. Perhaps others will have other ideas.

There are three ways to make it work:

1)Choose amps whose gains closely match.
2)Choose the higher gain amp such that it includes a gain control.
3)Insert a suitably chosen passive attenuator in series with the input to the higher gain amp, as Newbee suggested.

Be aware that if the solid state amp has a considerably greater power rating than the tube amp (or vice versa, although that would be unlikely), you will not be able to utilize a lot of the power capability of the higher powered amp. How much of the power capability of the higher powered amp that can be utilized will be limited by the clipping point of the lower powered amp, if you do not use an electronic crossover ahead of the amps.

There are a lot of prior threads about passive biamping. After reading them, you may conclude that the added complexity, expense, and potential pitfalls that it presents are often not worthwhile.

Regards,
-- Al

It can work, and I did it using Almarg's option 2. In my case, the ss amp has a volume control, which I keep at about "4." SS amp (190wpc) runs the bottom cabinets, tube monoblocs (60 w) run the mids and highs. A splitter from the preamp (Juicy Music Peach II) outputs is all I really needed. The sound is terrific across the spectrum. As always, your results may vary.