iMac audio issues

I have an iMac (model right before the first dual core) and have been running through an M-Audio Audiophile firewire eternal DAC for about four years. During this time, the internal iMac speakers by and large didn't work when selected in system preferences.

I now have an HRT DAC I would like to compare to the M-Audio DAC, and I can't get a signal to it. The HRT shows up in the audio preference list, but the only sound I can get through the iMac to the HRT is sound effects. I can also get sound effects when the iMac internal speakers are chosen.

I have disconnected the M-Audio and deleted all related software with no improvement. I think I have a software issue that needs to be repaired.

Anyone else deal with iMac audio issues.
go to: applications>utilities>Audio Midi

select the device you want to set up on the left. On the right you choose default and system outputs. Below that is you rate and bit depth.
A different problem but my iMac with HRT II+ connected, displays a message
usb device is drawing to much power and the usb is disabled or a dimming and erratic desktop that can not be used is encountered. HRT"s support web page is not working, an HRT distributor is looking into it. Has anyone else heard of this occuring?

Thanks for the reply. I tried your suggestion. Under the "Audio Output" section, there is a channel master and CH 1 and CH 2. The master volume is not highlighted, and I can't adjust it from the zero output setting. I think this may be the problem.

I tried the rate/bit adjustments, but no setting made any difference. I'm still left with the only working audio output being the M-Audio device. I think I'll have to take this in to the Mac store and show them what's going on. They claim they have never heard of this before.

Jazzybs, that doesn't sound good at all. Please keep me informed with any updates. I'll also let you both know how my situation turns out.

Thanks again!

try plugging the hrt into the actual computer, not the keyboard or other item

In audio midi> devices look for "properties for" your dac should be on the list in the pull down. Select it.

Then on the right select it as the default output. the system out put is usually best as built in (alerts go through internal speakers).

Double check that the format(rate) is acceptable. I prefer it as whatever the source is. Redbook (regular) CD is 41000.
set the bit depth at its highest, but if things still do not work you can try switching it to lower. Do not be alarmed. My guess is that you have the default output set on internal...

Yep, usb direct to the back of iMac (27" 3.06GHz OS X 10.6.4) it worked OK
initially. I have tried a different usb cable. and some basic diagnostics.
A powered usb hub does not work, Leopard does not see the HRT when attached to a hub apparently.

That's odd that Leopard doesn't see the HRT via a powered hub for you. That is not the case with any of the various HRTs I have had the opportunity to try out: the II, II+ and the Pro.

Do you use a Mac? Maybe I should try again before I return the powered hub.