What's wrong with my system?

Well, I don't have any photo sharing websites set up right now. But ignoring for a minute any issues in connectivity or speaker placement, does anyone think it could be an issue with system component matching? That I'm using the wrong DAC or amp for the speakers?

I never auditioned DACs apart from that Music Hall, but I did audition amps. I originally wanted a tube amp for more of that analog warm sound, but they were too slow for the speakers. The Arcam was much quicker and livelier with those speakers.

That amp is 40 watts/ch I read. Also an integrated which usually means smaller power supply, less current capable, etc. compared to separates.

SPeakers are average efficiency at best, not high efficiency that enables use of fewer watts for good bass.

Based on that, while stating I have never heard the amp or speakers, I suspect you would hear a difference in the bass at moderate to higher volumes using say a good quality 120w/ch or more power amp. Is there any way your could try a more powerful stereo amp or even monoblocks as an experiment? I would expect a difference. If it worked and you Arcam has pre-amp outputs, you could use it as pre-amp only still perhaps with separate power amp at first and see how that goes from there.

That's not to say the other potential setup or configuration issues already mentioned should be ignored. Those would have an effect as well regardless of amp used, so I would recommend making sure what you have is set up properly first before making any change. Then you will be at a good place to consider equipment changes/upgrades.

One other thing worth mentioning is that good bass is inherently a problem at low listening volumes due to our human ears. Its a normal thing but something that bothers some. The common solution in the old days was a "loudness" button, which provided an artificial bass boost at lower volumes, for better or for worse.

You want to listen at higher, more realistic volumes to better assess bass performance. Bass requires power so listen at higher volumes to best determine where any real issues with bass levels or quality might occur.

I looked through the descriptions and specs on all of the components, and the only thing I can add to Mapman's good comments is the possibility that the bass and/or treble control circuits in the Arcam are either misadjusted or malfunctioning. Have you tried its "direct mode" ("DRCT" on the remote), which removes those circuits from the signal path?

Also, like Michael (Swampwalker), I don't understand why reversing + and - to one speaker would kill the treble, but not affect the bass. In any event, to be sure that the two speakers are in phase with each other verify that a recording featuring a centered soloist results in a well focused image, centered between the speakers. As opposed to an image that is vague, diffuse, and hard to localize.

Regards,
-- Al

Can you try headphones or another set of speakers? How about connecting a sub-woofer to see if that produces bass? Or can you get some test tones and a db meter and see how the system measures?