Loud fizz with brand new Parasound Halo Integrated amplifier

Thanks so much, Erik.  I think you've zeroed in on the issue.  When I change the Macbook's output rate, the fizz gets adjusted (with some rates, it seems to go away; with other rates, the fizz is lessened; with other rates, the fizz is pretty loud).  

The Parasound is supposed to have a very good DAC, or so I thought.  Is the failure to lock just something that some DACs don't do, or do you think my Parasound's failure to lock indicates I just got a defective model?  I have about a week before I'm outside the 30-day period with the seller (Audio Advisor).  My big question now is whether, if I exchange my Parasound for a replacement of the exact same model, will the replacement be able to lock, or is this an inherent issue with the Parasound Halo Integrated.  What do you think?

Parasound says no drivers are necessary for Mac OS platforms. The Halo’s instructions say it’s just plug and play.

So a few things to mention:

1. I don’t know anything about DACs. Totally clueless, so I really do appreciate everyone’s insights and help.

2. I’m playing iTunes from my Mac. Most songs have an output sample size of 16 bit and a sample rate of 44.1kHz

3. When I plug my headphones directly to my Mac, the Mac says it’s playing the songs at 16 bit/44.1kHz, matching the music’s size/rate.

4. When I plug a portable FiiO DAC/headphone amp into the Mac’s USB, the FiiO’s screen says 24 bit/96kHz, though the Mac automatically says the FiiO is playing something slightly different: 32 bit/96kHz.

5. The Parasound has no screen, so when I plug it in, I don’t know what it’s doing. I do know that when I select among the Mac’s dropdown menu of formats, there’s now a bunch of choices: 44.1K all the way to 705.6kHz (each with 16, 24, 32 bit choices). When I choose the higher rates, like 705.6 or 384, I get the fizz). When I choose the lower rates, like 44.1 all the way to 96kHZ, I get less fizz, usually none.

6. The Parasound’s spec sheet says it supports DAC sampling rates "up to 384 kHz / 32-bit PCM.

7. When I say the Parasound doesn’t lock, what I really mean is that it doesn’t automatically pick a sample rate to accommodate the Mac (the way the FiiO does). When I first connected the Mac to the Parasound, I got tons of fizz. Now that I’ve followed Erik’s great advice about adjusting the Mac’s output rate, I get much less fizz. But when I do pick a good (i.e., non-fizzy) output rate, the Mac definitely stays on that rate.

So my two questions:

A. Should I expect the Parasound’s DAC to automatically find the ideal rate from the Mac? Or should it just allow me to choose (either wisely or poorly) like it’s currently doing? (I’ll exchange this Halo unit if I need to, but I won’t if I don’t.)

B. Assuming that I’m just supposed to choose the ideal output rate, what is that ideal rate? Should I set the output rate to match the iTunes songs’ rate of 16/44.1?

Many thanks to you guys. I’m new to this forum, and I already feel indebted to it.

I spoke to Parasound tech support, and they suggested that I play around with different output rates on my MacBook to find what works best with the Parasound.  The Parasound can pass up to 348kHz, but my iTunes files are all 44.1kHz.  So I guess I should set the Mac's output rate to 44.1 kHz.  Parasound said if I choose a higher output rate (96, 348, whatever), I'm upsampling the file myself, and that's not what I'm supposed to do.

What's weird is my little FiiO DAC plugs into the Mac's USB and immediately sounds good; I don't have to mess around with selecting output rates.  The FiiO just seems to make everything sound good.  What's throwing me off is that the Parasound forces me to select/experiment with output rates on the Mac to find a setting that sounds good.

Does all this seem right?