Not anymore, the early models did. Presonus will tell you there is no difference with the Jensen copy they use now . . . I actually have a unit that has Jensens in channel 1-2, and the stock trannies in the other slots, but I haven't used it in some time (studio construction and all, I'm working on wiring tonight) and I can't recall my impressions at the time I did the swap.
More critical is to drop in upgrade opamps, the slots are socketed so it's quite easy.