another Q: i wonder how the pioneer TA and alpine inbuilt TA and alpine digital processor TA all compare? hmm.

with alpine, those HUs fitted with 'bass engine pro' have TA. currently that's only the CDA-7878 MP3 player and CDA-7969. both retail for >$1500.
alpine's new range of HUs for 2002 should break the sub-$1k barrier for HUs with TA, so may be worth waiting.
the other option is to buy a secondhand (or even new PXA-H510 RRP ~$1200) alpine 'PXA' digital processor (eg: PXA-H400/600). you should find them around for <$600.
whilst they're best hooked up to alpine Ai-Net HUs, they can function perfectly well with non-alpine HUs. just means you utilise the (hardwired) remote for preamp control (volume, balance, etc) and can't use the digital inputs. overall offers the best value and they're a fine processor IMO.

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Alfa 156
currently being installed (when I have time...slowly!):
*headunit: Alpine CDA-7949E
*stacker: Alpine CHA-S624
*processor: Alpine PXA-H600 digital processor
*fronts: Dynaudio SYSTEM240 7" splits
*rears: Polk Audio EX602 6" co-axials
*sub: Polk Audio Momo MM120 12"
*amps: 2x Alpine MRV-1000 + Alpine MRV-T300
*power/cabling: Optima Yellow-top, Stinger cable, Lightning Audio 1.0F cap, fibre optics