240v Any reason not to use?

Wiring the amp for 240vac is a good idea.

It effectively makes the power supply in the amp larger and stiffer - which will help on creshendo and with complex passages, to whatever extent the amp circuitry can do the job. The power available from the amp will not change in any significant way.

I think you are playing things way too loud - 105 dB is way too loud for an average level. Way.

Average should be about 90 -92 at the listening position.

105db is just to see what the system can do, not normal listening levels. I just thought the system would go louder.

I was just wondering if all else is equal, why not use 240v.

Thanks
Marty

Wiring for 240V provides the benefit of *balanced* power; a great thing to have when you can do so. Aside from having half the current draw, noise floor should be significantly reduced. All of this may not yield the specific sonic improvements that you are seeking, but it certainly is not going to hurt anything in the least.
105dB SPL is just getting started at my house; I can do that with 2 watts/channel & still have about ~20dB of headroom. We can peak out >125dB SPL in the sweet spot, as measured with a lab grade meter, but no one can stand it that loud.