The HE version has a built-in regenerative psu. So it is more immune to noisy AC lines.

I use a simple trick with my r2r 11 mkii. I raise bit depth in Volumio to 24 using the highest quality setting. It gives a significant upgrade. The effect is likely smaller with the r28 nos but worth a try. Sw upsampling could also work. The di20he has a big impact on sound quality with the r2r...

Depends on the actual fw you have. Dithering and pll do not exist anymore in the latest iterations. "Dis" is just to turn the display off automatically when not using the control buttons.

It will work but if pressure it rather big on the pcb, you risk cracking traces. Also, it won't sound as well as if you would get it resoldered. It is approx a 1h job.

You risk cracking the pcb with time. Hire a tech or friend to take it apart and redo the soldering job on the transfo. Sound quality should improve also.

You don't really need both. Either one. To connect both, you need a 75ohm out of the Mutec to the di20he rca input. To connect a master clock, you need to get a 75ohm bnc (i think) for the Mutec. For the di20he, you'll need a 50-ohm bnc cable.

Push where indicated (first, take the cover off: remove the top screws, suction cups will help pulling it off).

It probably that the transformer's soldering job has to be touched up. If you put pressure on the transo and it comes back to life, this is what needs to be done. For it, the board has to be taken out.

I2S is not a standard thing. You may need to do some configuration.

What kind of connection?

The master-7 is an older design that actually uses the MCLK signal. Combined to an externally clocked di20/he or di24/he, you get quite amazing sound quality. It is also a good idea to use an isolation transformer to feed it.

Class t (Tripath) is better than your usual class-d. But a class a or a/b wins for treble, i am not arguing.

I tried a class T (tripath) with good results but prefer the nap250 in my office setup. The one with separate transfo on ali. The precision 3s should best it though.

Or this https://www.canuckaudiomart.com/details/650070323-audio-gd-precision-3s-power-amplifier/

On a budget, get something like this or a nap250-inspired amp https://fr.aliexpress.com/item/1005006068694011.html

Not recommended. Could work but only with sensitive speakers at low volume. Otherwise it can be damaged. I would not do it.

For not much money, the Zerozone pt500 should be fine. The pt700s would provide additional isolation. But given the price, I would use it on the sensitive audio gears: clock, DI, streamer and dac. The spo-500 is their top model, it features an o-core transformer (500w) otherwise it is the same...

The dac has one built-in but using an external one could help, especially if noise is very low at the output. Also, using an isolation transformer on the pc would help. It would prevent much contamination of the ac line. Or you can use the AC isolator on the dac. A PC contaminates the ac line...

Usb reclocker?

Yes, I think so. Especially if your source is silent.

80W would be more than enough for what I want to do but over 100w would be preferable to make the unit attractive. Anyway, I am just thinking out loud.

Yes, I second this choice.

Yeah. I could use a small set of monoblocks with matching response to the m3 to bi-amp. Something as refined as the m3 (or more), but less powerful, and with the same gain. That would awesome. 125w under 8ohm would be perfect. Weighting between 25 and 30 pound per block and with regen power on...

Seems like you described the discontinued A1. :) Sorry, not a monoblock.

Excellent, AFAIC.