How do I set this up ?

[JTurbide]

I'm about to put together a new setup.
Here is what I have so far (or at least ordered): SMS JG CTP, Hilbish beta preamp, mooer babybomb power amp.

Here is what I plan on doing:
I want to be able to run either preamp into a single power amp into a single cab (most likely 2x12).

So, for now I have a mooer babybomb power amp but I will likely upgrade for something else. I still don't have a cab but that is not a big concern on the technical side.
My question is how do I achieve my plan ? Does a preamp (tube or SS) need a load ? I don't think so but I'd like a confirmation.

If not, can I for example use an A/B/Y to send my guitar into both preamps simultaneously and then, both preamps into a Radial I/O or headbone, which would take the two signals and let only one go through at a time, into the poweramp? Then power amp into cab.

Would that work ? Any other ways to do that ?

[crochambeau]

Does a preamp (tube or SS) need a load ?

No, preamps are operating in a range that is inherently low current, and typically they are not transformer output coupled. It's only the high current (speaker circuit) + the transformer coupling that will induce a destructive inductive backlash in the output section of a tube amp when driven unloaded.

Line levels are fine, and most solid state amp circuits are fine running into no or low load (high impedance) situations.

That said, I personally would avoid running a tube preamp for extended periods without ultimately feeding an amplifier, as that's running the clock on the tubes, which are wear items. I wouldn't shy away from punching in and out between them in a performance setting though.

[backwardsvoyager]

The Radial I/O should be adequate, as it takes active instrument input and has a trimmer on IN 2 to help with matching volume.
You won't need an A/B/Y either if you have a stereo pedal you can stick last in the chain.

I'd be tempted to get a switcher that lets you blend the two preamps, though.

[JTurbide]

Good point about tube life. So I guess I could use it in A/B and stomp on both radial simultaneously to switch channel..

I guess my main concern is the Radial I/O taking the preamps out levels

Good suggestion for the stereo pedal but I don't think I have any. Blending the two preamp would not hurt the power amp or cab ?

[crochambeau]

I guess my main concern is the Radial I/O taking the preamps out levels

With the caveat that I have not played with either of the devices you mention, It's generally safe to say that preamp output levels should not harm a passive switcher.

Blending the two preamp would not hurt the power amp or cab ?

Blending preamps is what the summing stage of a mixer does, those signals are safe. In the most rudimentary form you can mix across parallel resistances tied at one end (I do this all the time). No harm will come from combining signals, but there may be a pronounced effect on sound quality depending on phase relation between the two output signals. Mind you, depending on the phase relation, the effect on signal can be perceived as detrimental or beneficial - the choice is up to you.

I do advise some sort of signal summing beyond a split conductor (Y cable style). I would think a self respecting A/B/Y box would include provisions to sum two signals without one source loading down another, which is a worst case scenario of the Y cable (resulting in unbalanced or tricky operation, generally not a source of destruction).