Thinking about a class D tpa3116 for my sub.

The amp on my powered sub psw10 is crapping out, I thought I could do a cheap diy fix with a 40W mono tpa3116(8?) Board from China. Add a 24vdc smps, and an op amp low pass preamp. Total cost would be around $15.

Am I crazy? I really like my system with the sub. I am using a DIY 6LU8 tube amp, without any sub out. I was using speaker level inputs on the powered sub.

I have a source selector that I built that holds my DAC board, and phono board. I can easily fit the low pass subpre amp inside the selector, and provide a mono combined line out to the sub. I would like to rip out the faulty amp in the sub and install both the smps and class D amp on the plate, use the e listing 120vac input to the sub.

Questions:

Will my phono and dac boards drive BOTH the sub low pass pre-amp?
Will the smps 24vdc/3A get too hot for installation inside the sub?

I know there are not a whole lot of specificshere, but in general, is this doable? I know it is likely not going to be high end, but I listen at very moderate levels.

Anyway, any feedback is welcome.

Roger
 
okay, a little more specfic
this board is all over Al Express. I know, I know, but I have used cheap boards from them, a DAC and a Phono stage, that worked out pretty well. it is based on a TPA3118. I presume that this board, while likely near the bottom of the line, will work for this application. And as it is for a sub, I cannot imagine that the distortion would be that noticeable for a sub application.
 

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You're welcome. On the SMPSU overheating topic I think its unlikely to overheat given you only listen at moderate levels. Music's average level is normally at least 10dB below its peak even on heavily compressed material. Meaning for a 40W amp you'll be hard pushed to get more than an average 4W out when driven with music, assuming you don't clip it. A classD amp is still fairly efficient at 4W out, unlike a classAB of the same power rating.
 
Now my last remaining issue is how to tie volume controls together. My main amp is an integrated 6LU8 DIY tube amp. Used with the high level speaker inputs on the sub, the volume control on the 6LU8 was controlling both.

I have to think about that. A couple of choices. Someone suggested adding a preamp out set of Jack's by tapping into the wiper of the volume control. While I like the idea, my chassis is very crowded around that space. A real nightmare to do that.