What sort of audio interface an what model of Tascam ?

Personally I'd be looking at a sound card with all the interfaces you want either built into it or integrated into a breakout box (attached to it). There is no need for a mixing desk unless you want to record multiple instruments at once and have run out of inputs. Also the next thing id get is a nice preamp as the pres on the Tascams are not the best.

I have been using an old 424 mk III as a mixing desk. It is a bit rough round the edges and is not in the critical recording path (i.e. between the instrument and the recorder) but it does the job I want it to and that is good !

As far as sound cards go avoid anything by Creative labs. The sound blasters are good for MP3s but little else.

You might want to check out M audio they are not bad however if you see anything by Hoontech or SKA audio run in the other direction. I am using an RME audio digi 96/8 Pad as my main sound card and it is lovely (~400 usd)

Hope this helps

S