Graveyard bump!
So I've had a combo of Alphalink Ax, Alphalink SX and the MX4 card for close to two decades now, and while SSL dropped support for them way too early (no updating of drivers) they've all been working good (minus some slight WDM driver quirks since I left windows XP or 7, still works though).
Half a year ago, my AX unit started showing symptoms; it would not start immidiately when turned on, but the lights would flicker. When left on for a while, it would turn properly on, and I've just left it on ever since. Until a power-outage a few days ago, where the unit seems completely dead, with no sign of life when turned on.
I presume it's a problem with the smps inside; without having opened it yet (middle of moving and busy with school), i would bet (without having extensive SMPS repair experience) that it's something to do with the electrolytics in the powersupply (based on fixing similar symptoms on other gear using SMPS, where swapping the electro's always brought them back to life).
Do you have some more details about the PSU? You mentioned it was 5v for the digital board, so I presume it's a 3-rail thingy, probably something like +/-15V and 5V? What current is it specced as?
I've been very satisfied with the setup, I still to this day haven't found a system with this many I/O of both analog, madi, adat and aes together with the best software mixer I've ever used on a soundcard (the MX4 is a beast! A routing sandbox where you can build your own mixer, all based on the building blocks we know from hardware mixers. Super intuitive, super flexible and awesome performance (2-4 samples or so?) with 128 "streams" (from/to apps), 128 buses (internal routing in mixer) and 128 madi streams... in each direction! It's pretty mad imo, and I've yet to find a replacement. Closest thing would maybe be RME Madiface FX, but TotalMix is such a downgrade compared to the MX4 mixer. It's really odd that it was cut from SSL's lineup, as it is amazing and there seems to be very few alternatives. Oh, and the Alphalinks sound good (maybe not as good as my Dangerous Music DAC-ST, but haven't done blind tests and we all know how accurate and unbiased opinions on converters are...) and offer amazing I/O variety and channelcount for the price.