[bxk1]

There is no way DIY diode bridge and filtering caps on a separate board could make a slightest difference here, in fact high frequency noise from the power supply could only be filtered right near the chip. But leveling up an amplifier, to a 4 times more powerful as you did, would make a significant difference in sound.

[tuatoru]

In fact there is a way or two.

The extra resistance (2 to 10 milliohms probably) of the wire between the two boards, together with the smoothing capacitors on the downstream board, acts as a low pass RC filter.

Also the capacitors on the PS board may be low-inductance types, and filter HF noise more effectively than the caps on the amplifier module.

Having the diode bridge further away from the amp module's inputs means the antenna action of the rectifier's leads is less effective: the RF power of over-the-air rectification transients at the inputs is reduced by the square of the distance.

The layout of the amp as shown is good, except that I'd shorten and cable-tie wires to help prevent hum loops.

[amluto]

I would suspect imagine that putting a power supply like this in the same enclosure could introduce unpleasant noise. There will be a big current spike every half cycle when the rectifier starts conducting. The power factor will be awful, and I can easily imagine 120 Hz and its harmonics coupling somewhere you don’t want them. Not to mention that you might be able to hear the power supply buzzing.

Get a nice AC-DC converter brick and call it a day. If you want to be fancy, stick a linear regulator on the output.

[tuatoru]

If Apple or Dell sold 36V 10A power bricks, then maybe.

The ones that I've seen don't put out their claimed current, lose regulation badly at high load, and put a lot of hash on the DC rails. Seriously ugly. Opening them up, the circuit design often looks like it comes from the 1980s. Physical design usually doesn't meet standards for HV separation and creepage.

Rather than a linear regulator, lots of filtering (a few 100nF ceramics and a few millifarads of smoothing) would help. And a high-powered TVS or two for when the power brick dies, as it will.

[amluto]

Apple or Dell? I would start with Meanwell if I were trying this.

[Hydraulix989]

TPA3251 is the best on all performance