I have just finished the install of the 1.1000 and 4.150 in my XB. First the 1.1000 blows away by SoundStream VGA800.2 running my Ascendant Ava 12. The base is much more defined and more musical without losing any of the low end. I have read a couple of reviews where the 4.150 did not have much mid base, but that seems to be way over hyped. I am running this amp bridged (300X2) against my CDT ES 643 with upstage and the mid base is perfect. I will say these amps have a very flat signal that in no way changes the music from the head unit. I have the Eclipse 8455 and with these amps my EQ is set to OFF!!!! and the sound is dead on. As for the mid-bass, I do have JL 6W0s in kicks which off set any loss that I might have, but I did have to adjust the crossover higher and the gains down as the CDT 6.5s were nearing fatal excursion. My two cents...
Re: Alpine PDX
love the pdx1000 the pdx4.150 could use a little bit of work imo..great amp though but i did motice the lack of low end from it in the 2 systems i tested them in... not at all drastic but it was there not what id recc for a full out iasca sq car..