I'd go with 4v pre-outs personally. The way i see it is that you want to keep the gains as low as possible, and feed the amp with a higher input signal.
The amp should run cooler and draw less current when idle.
Here's an anology... You have a lightbulb controlled with a knob style rotary dimmer that clicks to turn on/off. Just click the dimmer on, don't turn it past the click. This is the gain turned all the way down. Now, as you begin to turn the dimmer and make the bulb brighter you're doing the same thing with the gain on the amp. This is turning the transistors on with dc instead of signal. The problem is that this level of brightness shall we say, is the zero crossing for the sine wave. This effectively reduces the headroom for a signal transients in the amplifier circuitry.