Issue on Luxman 507ux II XLR balanced input ?


I have just bought this new Luxman 507ux II amplifier to replace my Yamaha A-S2000

I use as a source the same Hegel HD11 DAC, on XLR balanced output, to Luxman's XLR balanced input BAL-1

I quickly realized that, while this was perfect with the Yamaha, it did not sound correct on the Luxman.

A feeling of a too large scene, abusively extended stereo, aunclear voices .. Hard to define but not satisfactory. Even my wife told me that the sound was not normal and not clean. Considering the price of this unit I was a bit pissed off.

I realized first that the phase of XLR was not the same on Hegel vs Luxman, hopefully the Luxman amp has a swith to invert cold and hot on the back, I thus moved this switch to "B" (vs "A" by default)

Not real improvement of the sound. Do not ear any difference.

By the way when I move this phase switch while playing I do not hear any sound glitch or cut .. Must be a digital thing .. I have no schematics.

Then I tried the non-balanced RCA link from the Hegel DAC to the Lux 507, and it immediatly sounds far better, "normal" I would say.

My analysis is that the Yamaha was a full balanced design, so the "best" input was XLR, while Luxman is not a full balanced design, so XLR signal must first go through an unbalancing stage, the non balanced input should be naturaly better.

But really, the difference is so obvious, I can not believe it.

I checked specs and I do not see explanation

I still have to test BAL-2 input to see if it is similarly bad as BAL-1

Does one of you use XLR input of Luxman amp ? From what source ?

Did you experience such issue ?

Thks fo reading and sorry for my incorrect english, not so bad for a french guy.


Hi, I feed a 507ux from a Mytek Brooklyn and it sounds great. The cables I use are single strand pure silver with silver contact XLR plugs on both ends.

The sound quality of "fully balanced" vs. normally balanced should not be that much, so I'd put that idea off for now.  If the sound quality is significantly reduced I'd look for another less esoteric problem.  

Get a cheap pair of XLR cables to compare the  sound of to whatever you are using. 


You must be right. There is a difference between XLR & RCA, but it does not explain all. Some plays that were highly appreciated with the Yamaha A-S2000 now sound cold and hard (whil being more detailled). Can't explain. My speakers are about 92/93dB sensitivity. I have two pairs with slightly different sound print, and same issue with both (brand Cabasse, one closed, one bass reflex)

Will take time to proceed to cross checks with another amplifier, another source, and speakers position change.

I feel like returning the amplifier .. or at least going back to the shop and my source and listen with the seller. If the issue is not "major" and remains subjective I might have difficulties to have the units replaced ..

Well .. issue solved, and it has absolutely nothing to do with the Luxman

I am using a Raspbary PI as an USB source to a Hegel HD11 DAC since years with satisfaction.

The USB Pi runs Squeeezelite, an open source version of Logitech Squeezebox.

One month ago, during a major system upgrade, all crashed, and I reinstalled a bit too quickly. I forgaot to route the data to HW (SW untouched) audio input, and it remained routed to ALSA SW stack.

Also, this device never reboots, so for a reason I ignore, it case to a status with a downgraded sound, propably some bad synchro or packet loss... unclear.

After de reboot all came back OK, and I redid the global setup to HW bitperfect output this time.

All sounds great, even magnificent.

Only I have to say the RCA and XLR inputs of the Luxman sound slightly different.

The HEGEL DAC natively output in balanced, the unbalanced output is "lower", and in opposite the Luxman natively is unbalanced, the XLR balanced input goes to an unbalancing stage that certainly downgraded a bit the sound.

Listenning with several friends, we prefer the RCA path ... by a small margin.

Thks, and sorry for having worried Luxman fans, it is a super product.