Reader Branko asked me privately what brand/type of USB preamp I'd bought, because he too wants to digitise his vinyl record collection. I'm really the wrong person to ask, because the entire comparison shopping process for me was to go to Okaphone, a local electronics store catering to DJ's, and ask for the recommendation of the guy behind the counter. He told me they had two models in store, they were both the same price, and people had the best experiences with the one from JB Systems, so I bought that and got to work.
It didn't make sense for me to put in more effort, because
a) I'll be leaving the country again in three weeks and don't have time for agonising over specifications and price/quality ratios (beyond what's obviously sensible) if I'm to get any digitizing done; and
b) The other components aren't exactly of audiophile quality. The weakest link in my audio chain is the turntable, followed by the speakers, amplifier, room acoustics and my damaged ears.
The turntable is over 30 years old, the automatic start/stop no longer works well, the platter scrapes the console deck when I place a 180 grams vinyl record on it before I let the needle drop, and it's only a matter of time before the next issue rears its ugly head. In fact, I had endless fun, for a given value of 'fun', over the weekend trying to figure out what was making it sound so fluttery all of a sudden. I bought a new, shorter belt for it, which worked well with my LPs but caused horrible machine rumble with 45s, so now I switch between the old belt and the new belt whenever I need to change the rotation speed. I get good sound out of it all but it takes a lot of work, and if I wasn't going to emigrate within a year, I'd definitely replace the turntable. Luckily, the cartridge is new so I won't have to worry about that.
The sound card on my MacBook is good, and the USB device seems to be doing a good enough job. I'm satisfied with it under the actual operating conditions I'm working in.
So my advice to Branko is not to sweat the choice of A/D converters too much but make sure your turntable is OK—is the cartridge new and of high quality? Is your drive system (belt or direct) dependable? Also, are your records clean? Mine are, but my mother's still have dust on them after repeated cleanings with different methods, and it is affecting their sound. I am pretty sure that all things being equal, those will affect your experience a lot more than doubling your expense on the A/D converter.