XPA-2 / XDA-1 causing hiss?

[juztaylor]

I have a pretty basic 2 channel set up that i use for music and movies consisting of an XDA-1, XPA-2 and MA RX6s. Sources are lossless files from iTunes via Airport Express

To me it a great set up. Detail is amazing. But a couple of things have been annoying me a little lately:

I am getting a very faint hiss with no source feeding the MAs. If the volume is off (on the XDA-1) i don't hear anything, but if i have the volume up just to 0.5 then i get the hiss. The hiss doesn't increase in volume the higher i turn the volume up.

Also, i am beginning to think that it may be a little bright with some of the trebles not sounding that great (i am no audiophile here).

Is the hiss from the XPA-2 or the XDA-1? Do you guys have any ideas how i could 'warm up' the sound a little? XSP-1/USP-1 maybe? Another preamp?

[AudioHTIT]

I have had an XDA-1, and now an XDA-2 driving my amps and have not heard any hiss, but my speakers are pretty low efficiency (86 dB). If the hiss goes away when the volume is all the way down it would appear to be from the XDA-1. You might try an unused input and see if the hiss changes when an empty source is selected.

As to the sound, what level do you normally listen at? Do you like the sound better when it's louder? If you regularly listen below 60 on the XDA-1 you might consider an XDA-2, I have found an improvement at low volumes, at higher levels the difference is less noticeable, but the ASRC jitter control can also help. If you never open up the XDA-1 (say above 65 or 70h then attenuators might also help. As for warmth I use tube power amps and they warm up my room nicely (j/k I can't feel them),

[garbulky]

I have the XDA-1 and the UPA-2. I would reccomend 12 db Line attenuators to cancel out the hiss. For me they also smooth out the highs and help with dynamics that makes it analog like. There is a sound signature change that is beneficial to music (not so much for movies).
www.parts-express.com/pe/showdetl.cfm?partnumber=266-244
The XLR attenuators can be found by searching google. Whirlwind has one as well as several others.

[juztaylor]

I have hear attenuators may do the trick. Something like this then

www.binarydesigns.com.au/bdstore/ATT448.html

Would 20 db be appropriate with the XPA-2?

This may be a stupid question, but would adding a pre-amp help with this at all?

[garbulky]

I've never used a pre-amp. The XDA-1 has a lossy digital volume control which means when you turn the volume down low from its maximum output audio information is lost (at low volumes). A pre-amp will get around this issue. However, I don't think it will solve the hiss.
I don't know if 20db is appropriate. I know XLR outputs at a higher voltage range so....probably

[juztaylor]

OK. Will order some attenuators today.

I still don't know about the 'warmth' aspect yet. Maybe i should just see if the attenuators make a difference and if not then consider changing the XDA-1?

[dean70]

I dont think the XPA2 would cause hiss. More likely to be the source - I have a HTPC connected directly to the XPA2 & there is so little background noise I have to take the grill off the speaker and put my ear right next to the tweeter to hear it (thats with 93db/w speakers).

The receiver I had previously hooked up as a pre-amp/dac made a small amount of hiss through this amp (using the same RCA interconnects) - maybe it is an impedence issue?

[pedrocols]

I have to admit I did not like the attenuators at first but they are growing on me. I played with my speakers' placement a little ;-)