That doesn't surprise me that the H-02A sounds bad. It might have some potential, but I don't know if it would even be worth buying considering the overall low quality of everything inside XS amps. I'm also starting to think that they must utilize used parts. The stock RCA jacks on mine where horrendous, most of the ecaps were dented and scratched, and a lot of the resistors are chipped and scratched.
Those Vishay caps look nice! They're massive.
What type of resistors did you use?
I really want to try some Fairchild Stealth diodes in the PS soon.
I don't know if I'd change the values of the ecaps. I would be worried about how that would affect the circuit. If anything I'd just upgrade their quality, but use the same uF value. Maybe someone more knowledgeable can comment on this.
Which Rubycon series are you referring too? They make some excellent ecaps in a variety of series, but they are mainly lower voltage it seems. For the two PS ecaps (the big 330uF and the 33uf) you can use whatever you want as long as it's rated for 450v. Nichicon, Xicon, Vishay/Sprague, United Chemi-Con, and Mallory all offer caps in both these values rated at 450v and are available from places like Mouser.
Unfortunately the Switchcraft 1/4" jack doesn't have a part number on it, but as long as it will fit through the 8mm front panel you can use whatever. I'll try to find out the PN for it.
The pin-out for the volume pot will depend on which one you use. The only wiring diagram I have is the one that came with my ALPS RK27. When you finally get one I'll help you figure out how to hook it up properly.
For the switch I went with a GC #35-024 On-On 3PDT mini toggle. I think the easiest way to explain the wiring procedure would be to draw some pictures so give me some time. It's not hard at all, just hard to describe; a picture is worth a 1000 words right?
Do you have a PayPal account Marcus? If you'll pay shipping I could send you a small parcel containing the harder to find parts like the ELNA caps, the HV ecaps, and the TRS jack. I could also include a GC switch and the cheap NTE resistors for the PS if you'd like. PM me if you're interested.