SilverEars, that amp will be more dependent on the power supply than anything else. You have a great spot to use those regulators. lm317/337 aren't the absolute quietest but plenty quiet enough, easy to use and responsive if configured properly. Start with a rectified V of at east 1/2 again your intended V and then regulate down. Don't use a switching supply to start or you'll kill it. You can probably find something better sounding than those aluminum caps for their function as well but premier electrolytics will be a bit larger. Replacing 2 resistors per channel to change gain and taking one leg to ground to remove a balanced input is the common way to do almost all amps. No V control? and if so is it at the input? That works fine but isn't optimum. Probably should still be capacitor coupled at the input side to block source DC, especially if using a pot. DX90 is also DC coupled output.
I know you're excited about the project but probably not in this thread until you hook it up to your DX90. Have fun.
Edited by goodvibes - 6/27/14 at 5:53am