Most of the comments here have singled out the speakers as the problem. I found a site for
Genesis speakers, but found no model 2815. Genesis seems, at first glance, to sell decent speakers. Does any one have a link to more info on the model 2815?
On the other hand, i found plenty of info on the Sony STR-K7000 receiver - none of it good. Ebay lists many of these for sale - there is probably a good reason why. Without more info about the Genesis speakers, I think the receiver is the source of the problem. It is an inexpensive HTIB receiver. Most sites did not mention rated power at all, but one site said it had 28 watts/channel
!
Even by Sony's usually inflated power standards, 28 watts is unusually low. I could not find detailed power ratings for this receiver, but I suspect it is underpowered in a big way. Other Sony receivers that I am more familiar with stated their rated power at
40 Hz to 20 kHz at 6 ohms. If power was measured by the more standard 20 to 20 kHz at 8 ohms, it might be considerably lower.
I think this easily explains why the bass response is missing with the new speakers. This receiver was designed to power only small satellite speakers that will not produce any bass below ~100 Hz.