You can use two preamps as long as you balance the gain on the preamps to have enough headroom, so the audio signal doesn't clip or distort.

Can you use two preamps?

You can use two preamps as long as you balance the gain on the preamps to have enough headroom, so the audio signal doesn't clip or distort. You can either connect the preamps in series or parallel and mix the two tones together.

Can you connect a preamp to another preamp?

Short answer, Yes. A preamp can be used with an integrated amp. Ideally, you must connect the preamp's output to the Main Input of the integrated amp. This will bypass the integrated amp's built-in preamp.