[rustbucket]

Hi All,

I'm running Linux (Kubuntu 7.10 specifically), and was wondering about the best way to configure audio playback. I'm currently using Amarok with ALSA set up to output to my Super-Pro DAC over USB. Sound quality is good, but I get clipping on tracks that are recorded 'hot' if I put the volume slider over about 50%.

I also have a Chaintech AV-710 that I can use, but I haven't had any luck getting the SPIDF working.

So I really have two questions: What's the best way to configure Amarok/Xine for playback, and what's the highest quality link to my DAC, USB or optical?

Thanks for any help!

 

[cerbie]

Are you clipping at the output of the DAC, or the input of your amp? Do you have a DMM?

USB is fine. But if you want better, and you're not getting skips, there's I2S, which it allegedly supports via the RG45.

 

[rustbucket]

I think the clipping is at the DAC output, as I can hear it no matter what the volume is on the amp, but I could be wrong.

By DMM do you mean a multimeter? If so, I have one. What should I be measuring?

 

[Bizzel]

In terms of linux drivers and mixer settings, I sidestepped the issue using a Squeezebox and its Slimserver software to do away with the need for a sound card. Maybe that's something you could look into as it ensures bit perfect audio on linux.

 

[rustbucket]

That's a cool product but for $300 I could seriously upgrade my Super-DAC->PA2V2->HD-280 system!

 

[Bizzel]

Bring up the mixer, what's the PCM/wave volume set to? Too high and my sound card used to distort like crazy!

 

[cerbie]

PA2V2 as in pocket amp version 2, running off of 2 AA NIMH batteries? If that's a yes, try it, instead, straight from the DAC, with the RCA->1/8" adapter, and see how it goes.

2 NIMH AAs give you about 2.5V charged and rested, and you'd need R-R (rail to rail) opamps to get that kind of swing (+1.2V or so), which it looks like the PA2V2 is not using. So, try no amp, first. If it works OK (it may be distorted in other ways than clipping, but that is fine if it happens), then your amp is your new weakest link.

If not, you could try measuring Vrms (AC voltage) over one of the output channels with a sine wave being played, but that can get a bit more complex, and I don't really know exactly how cheap DMMs respond to clipping with their reading, save that it probably would stop smoothly rising.

[size=xx-small]*grumbles about Paypal*[/size] It'll probably be another week before I get mine.

 

[rustbucket]

That's the amp - I've been realizing over the past few weeks that it was a shortsighted purchase as I'm learning more about what's out there. Part of the quality loss is through the crappy Y-adaptor that came with the amp. Using a RCA->3.5mm cable to the amp smooths things out

Listening through the DAC directly sounds better but still definitely clipping. I'm using "What Am I to You", by Norah Jones as my reference song - it's low key nature really highlights the sound problems. A volume level of just 11% is plenty loud.

Currently the best sounding setup is through the amp using a decent cable. With a good quality RCA->3.5 adaptor, I think that would change. I'm going to test that theory by picking up an adapter tomorrow.

On the mixer, the PCM and Master sliders are at 100%, but going through the DAC they don't do anything (I'm changing the settings in Amarok itself to use the DAC). I don't know how the volume level in Amarok interacts with those settings, but I've been getting pretty good results by keeping it below 30% or so.

I wish i could figure out a way to keep Amarok/Linux from doing any processing of the audio signal after decryption. Given that twiddling with the sliders makes a difference in the clipping, I'd like to just get them out of the mix. Correct me if I'm wrong in thinking that changing those percentages could have a serious (and difficult to measure) effect on the sound...

 

[geardoc]

To get the spdif output from my Chaintech AV710 I had
to use hw:1,1 in my .asoundrc file.