System Upgrade

I agree I have totally different gear. Nonetheless, the most obvious problem that any of us can diagnose on the internet is that his amp is underpowered for his speakers. You need a solid 80 watts for the SHL5+, 150 for larger rooms. As someone else suggested upthread, this can be easily tested without much cost or effort (order a 30 day trial or borrow an amp).

I suppose room placement is another easy and free thing to investigate, but whatever the case, the amp is underpowered. Speculating about warm voicings and such seems to me like medical diagnosis by text message.

Its the efficiency , MORE power . 

No its not just power if  you follow that for these speakers you should be able to get

86db  1w 1m
89db  2w 
92db  4w
95db  8w
98db  16w
101db 32w 

You might start to soft clip but unless you are not able to get a decent volume level the issue is not power.

When you have to raise the volume to hear detail and get any drive you have a lack of resolution.

This is not to say these are not all excellent components tbey are all voiced on the richer side of things.

Borrow a set of Nordost cables,  between the dac and a set of  Nordost speaker cables and then see how the system sounds. 

Dave and Troy
Audio Doctor NJ

I'm gonna go with 

a) manufacturer recommendation
b) peak transient power used in this video with the M40.1s as possible indication of power needs.

https://www.youtube.com/watch?v=bRMR9JZ1m0s

rather than kilobuck cables.  YMMV.

Very helpful, thank you. Will be test running with an Amp. At min. 150W, but more likely 300W. Possibly change some cables.