Just throwing in my .02. If you like the sound of the tape deck thing (which IMO is the closest thing to vinyl in terms of "lo-fi" shaping), then stick with that. BUT, find a good deck like a Nakamichi or a Revox (can be had on ebay for cheap) that has two things:
1) 3-Head design (enables monitoring off the playback head in record mode)
2) Adjustable record bias control.
What this will allow you to do is to send the signal out of your PC, into the tape deck, and back to the PC while the deck is in record mode. The signal will hit the tape, immediately be played back (with a short delay) and sent back to your PC for processing. The adjustable bias will allow you to control the "color" of the signal in real time as you play the source back. You adjust the bias while in record, and immediately hear the result printed to tape while monitoring. Not to mention the type of tape in conjunction with the bias adjustment will give you a wide pallette of different tones to choose from.
So now you have two options. Either print your signal through the tape deck to track, then nudge the track to compensate for the delay. OR, nudge the track thats going to tape backwards while listening in record-monitor to get the timing right. So alls you do is keep the tape running and youve got a continuously adjustable "bias-box" that will flavor the audio to your likings.
If you really want to get crazy (or if your ALL sequencer based), setup delay compensation in Reason to delay the playback of everything versus the signal your "processing". So now you've got PSP VintageWarmer on STEROIDS HAHA.
Too confusing or involved?
The ART TPS dual-channel preamp is your ticket. The V3 (Variable Valve Voicing) technology in that thing lets you choose what type of "dirty" you want and will deffinately give you the saturation you're looking for. You can actually (if you're careful) get really tasty, usable "clean" sounds out of that box. A better power supply with that unit really helps for this.
Anyway hopefully I didn't lose you.
Help much?
Holla
~the kid
BTW, at about $200 on the used market the TPS box is not a bad paintbrush to have around, ya dig?