Luxman 509x vs Hegel H390

The big reason for the 509 vs. the 507 is low impedance speakers.  The 509 is a little stiffer where your speaker's impedance dips thanks to the beefier power supply and another pair of output transistors.  Both great amps.

I have the B&W 705 Signature bookshelf speakers. So, either one in the power output dept. should be quite sufficient. Now , it all just really comes down to SQ, both have some terrific reviews then just a sprinkling of not so stellar ones. 

For the Luxman 507 , just how much does it give up to it's sibling 509x in terms of transparency, detail and air between the instruments/vocals . With that in mind , does it have the edge there or lack of compared to the Hegel H390?. 

As for the Hegel H390, why so many on the used market anyhow, putting the issue of aesthetics in the long term , are people selling due to a tiresome possibly dark and dour SQ in time ?. 

Those are two great sounding amps. I went with Luxman, but only because the Luxman had some added features I liked that the Hegel did not have. Sound-wise? The Hegel might have an edge on controlling/powering full range floor standers, due to the extra power, but I have large bookshelves and a powered sub, so it's not a problem for me to crank it up. Wish I could give you more on a sound difference, but honestly, you won't be disappointed with either.