Accuphase E650 XLR Input issues

I'm asking on behalf of a dear friend, he has an Accuphase E650 which was used on RCA input without any issues, recently with an upgrade of the source, XLR was chose as the preferred connection.

It works fine initially, however just after few days, the left speaker start to sounded noticeably softer than the right, sometimes it normalise sometimes it stay on as is for long period of time, these were done as isolation steps:

- Continue to use RCA input, works consistently

- Swap left / right XLR input, still the left speaker softer noticeably

- Swap different DAC with XLR output, still the same behavior, left speaker softer noticeably

- Tried different XLR cables, still the same behavior, left speaker softer noticeably

- Tried both the XLR preamp input (CD-in, and Balance-in), same behavior, left speaker softer noticeably


Ran out of options, the challenges was the amp was purchased from an oversea distributor, getting local dealer support can be a hit and miss, trying to post this up to see if anyone ran into such issue before and also seeks some opinion.


I realize that you mentioned that all works perfectly with RCA inputs, but perhaps try changing Left vs Right speaker cables on the amp side (only) to make absolutely sure that the issue is not with the speakers or speaker cables.

Also perhaps you can speak to Accuphase support..

Good luck

@lalitk et al

hey folks, i am sorry -- i didn’t mean to cause undue consternation

i bought a used e270 couple years ago and felt the balanced input did not sound as pure as the rca input, to my surprise (i had a couple dacs at the time that had both single ended and balanced outs and i could hear the difference in my system) - i did not personally try the higher up models, and perhaps those are immune from this issue

after that experience i saw the following information on the asr site -- please note that i am not a ’measurements guy’ in the least, particularly with respect to using measurements as a proxy for sound quality of any given component, but it was interesting to see the findings solely in regard to noise level in the preamp section and thru the xlr input of this tested unit

i also spoke to usa importer briefly on this topic and confirmed this was an area that accuphase japan was working on, as traditionally accuphase gear was exclusively single ended in design, with no balanced connections

thereafter, with the announcement of the replacement model e280, accuphase themselves mentioned that one of the notable improvement areas was in the balanced input noise level - see below page 5



Thanks all, will try any other avenue and see 

@tecknik  the issue is the cable work just fine consistently on right and have swapped cables left and right as well 

@jmarshak speakee cables has been swapped left and right at the amp side as well


i just want to be clear and say that i have tremendous respect and liking for accuphase gear which i have owned on several occasions in the past

it is wonderful gear, so beautifully built and sound quality to die for

my initial response to the op was specifically on the narrow topic of xlr input implementation in their relatively recent pieces

my experience otherwise with accuphase amps have been wonderful, and they have been utterly reliable and absolutely built to last a lifetime