No low-end with Kenwood Excelon KDC-X502

[gamora77]

Forgive the long post, I'm at a loss here and trying to provide as much detail as possible to hopefully find a solution.

I bought an '02 Dodge Dakota RT last year as a second vehicle -- not a daily driver so I wasn't looking for a crazy sound system. It came with a stock HU, but with aftermarket Alpine 6.5" drivers front and back (and 2" tweeters up front). With the stock HU, I was very pleased with the low-end delivered by the Alpines. They delivered a solid thump with my preferred music styles (rock/metal).

I wanted Bluetooth and a couple of other frills, so I replaced the stock HU with a Pioneer DEH-S5000BT. The Pioneer delivered great low-end performance, essentially identical to the stock HU, with all settings at 0 -- EQ set to "natural", bass boost and loudness off, etc. But it had an unrelated (and apparently common) factory defect in its faceplate connector so I had to return it, and I replaced it with a Kenwood Excelon KDC-X502.

The X502 generally sounds great, but the low-end is virtually nonexistent. In testing, I turned on all of the options that should deliver ugly but loud bass, including setting the preset EQ to "powerful", setting Bass Boost to level 5 (max), and setting Loudness to level 2 (max), but I'm still getting almost no low-end response.

Switching to manual EQ and setting the 62.5hz band to its maximum value DOES seem to correct the problem to some extent, but I can't help but feel like this shouldn't be necessary just to achieve low-end performance that's only-just-barely comparable to the zeroed-out Pioneer or stock HU... this feels like a band-aid fix for a more fundamental problem.

Other random details:

I installed both the Pioneer and Kenwood HU's myself; I used a Metra 70-6503 wiring harness and soldered/heatshrinked the connections

no amp; using stock wiring directly from HU to speakers

problem seems to be independent of selected source; same problem with Bluetooth and CDs

front/back HPF freq is set to "through", tweeter freq set to 4KHz

front/back speaker sizes are set to 6.5" and subwoofer set to "off" (as I don't have one)

car type is set to "compact", sound realization to "off", space enhancer to "small", sound reconstruction to "on" (but toggling them makes no measurable difference)

I have tried tweaking virtually every setting on the HU and nothing aside from the manual EQ seems to make much of a difference. And I've been careful to make apples-to-apples comparisons, listening to the same CDs with the stock, Pioneer, and Kenwood HUs, and to the same tracks via Bluetooth (using the same phone) with the Pioneer and Kenwood HU's.

I can only assume I've screwed something up, either in the installation or configuration of the HU.

So my question is: What am I doing wrong here?

Thanks!