Hello,
I am also using the stock Transporter with some personal upgrades going direct to Cousin Vinnie's wonderful 30.2 amp. I found the combination very challenging. More or less resolution with TP volume, more lower midrange fill-in (30.2 as default vol=) with more bass and less digital signature. Its been great experimenting with both and now I have settled into a nice combination between the two.
Vinnie thanks so much, pal.
Luis