I'm trying to build a pre-amp with both analog and digital imputs.

For the analog stage, there will be a relay volume control and a buffer, giving at max 10.2 dB of differential gain. Meaning 2x1V in, is 2x3.6V out. I can lower these settings a bit.

Now for the digital stage, I'm going to use the digital volume control of the Buffalo, and bypass the buffer used in the analog stage (why use it if the Buffalo has it's own :) ). However, the default output is 2V RMS, meaning that that would be to low to be on par with the analog stage.

The Buffalo manual tells about lowering the gain for less output, but does not tell what happens if you raise the gain...

Can anyone tell me if it is safe to do this? And if so, how far can I go, and what impact will this have on noise and THD?

Edit:

Well, to max out my amp and use the maximum volume control width, I'd like to adjust the gain of both amps so it will not tip the rail voltage (110V p-p), so a safe margin of 100 p-p seems to be fine, that is about 35V RMS. The gain of the amp is 26dB, so times 20, meaning input should be 1.75VRMS? So then I would actually need less gain, like adding 1.8K resistors ;)

Or would it be better for performance to leave the gain as is, and just use less volume control range?

Edited by user Monday, January 25, 2010 2:35:51 PM(UTC)  | Reason: Not specified

Yes, I guess you're right. I will just lower the gain of the analogue buffer to match the DAC (as far as possible, since I'm dealing with various sources anyway).

But just in theory, what would I gain by increasing gain to have, say, 7 V RMS?