Intega P-303 and Onkyo M-8000

JBL is known for having great, powerfull bass extension, but I don't know the model you're refering to, I searched the net and found nothing.

Maybe the problem is not the pre or the amp, but your room acoustics. Are your speakers rear ported ?, have you tried different positions ?(I mean for the speakers lol), are they too close to a wall ?

Rgds.

Thanks Foxtrot. Yes, the speakers are rear ported and located close to the wall. Are these major causes? Bill

Bill, rear ported speaker ''fire'' bass to the wall, if they are too close to the wall no doubt you're getting that unwanted bass response.
If your room alows it, try moving them further from the wall and play a little with the postition.

Tell us if you hear any difference.

Good Luck.