I also do use tweaks A lot. As long as they are sensible.
I installed a low jitter masterclock in my CD player, with it's own power supply.
Gave the digital circuit it's own 80VA toroidal transformer, with shottky rectifiers, and nichcon KG buffers.
Also i split up the power supply and divided, so each chip got it's own regulated low noise feed. Spdif, decoder, dram etc, i removed the system clock, and gave each chip that needed it it's own low jitter clock.
The tweaks work. It changed my former mediocre Marantz CD72SE, to a really singing highend player.
Although i now use a seperate dac now, modding the player to use it as a transport, was beneficial.
The cleaner the spdif signal enters the dac, the better it sounds...