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Q I read lots about digital to analog audio converters (DACs), mostly because of high-res computer audio. Here’s my question: Why do some DACs have a digital output? If the purpose of a DAC is to convert a digital audio signal to analog, why would you want it to output the signal in digital format as well? —Jacques Simard

Q I want to get better sound when watching movies on my new Panasonic ZT60 plasma TV. (I stream a lot of Netflix and Vudu via the Panasonic’s built-in apps.) To that end, I recently bought a small stereo setup: an NAD C326BEE integrated amp, a Musical Fidelity V90 DAC, and a pair of Monitor Audio Apex 10 speakers. The only way to connect the TV to my audio system is by using an optical digital output from the Panasonic to the DAC, which then connects to one of the NAD’s stereo RCA inputs. Here’s the problem I’ve been having: When I watch Netflix or Vudu, I hear nothing but static noise coming from the speakers, though the sound is fine when I watch DirecTV (I have my satellite receiver connected directly to the TV via HDMI). This noise went away when I switched from 5.1 to 2.0 audio in Netflix, but I don’t get the same option for Vudu. I’m kinda stumped at this point. Shouldn’t the Musical Fidelity DAC automatically dumb down 5.1 signals to stereo? Is there another possible configuration that can solve my problem? —Gilbert Solis / via e-mail

Q Most movies on DVD and Blu-ray default to 5.1 surround sound, but most concert videos default to 2.0 stereo, and the viewer has to manually select 5.1 surround when playing the disc. What’s the reason for this? —John Kellam / Tucson, AZ

Q My system consists of Aerial speakers, a Rotel 5 x 100 watt amp, a Marantz AV-7701 pre/pro and a Panasonic Blu-ray player. All my music is stored on a Mac computer and streamed to an Apple TV which is connected by an optical cable to the processor. The sound with movies is fine, but digital music lacks detail and has no WOW to it. My car’s Krell audio system sounds far superior in comparison. All music files on my Mac are in 16-bit WAV format. What am I missing? —Roland Bertha / South Florida

Q I'm a proud new owner of a Marantz AV7703 preamp/processor, which I use with a 7.0 speaker configuration (full-range fronts and no subwoofer).

Here’s my question: When I play a Blu-ray disc with a 7.1 DTS-HD Master Audio soundtrack, the pre-pro’s auto surround mode outputs it as DTS-HD + Neural:X (see above picture). But why would the processor create an upmixed signal instead of passing on discrete channel information to the back surrounds? I’m using an Oppo BDP-103 Blu-ray player with the audio output set to bitstream. —John F. Bartelt

Q When I switch to the Netflix app on my Sony TV, the receiver doesn’t switch to ARC; it stays on HDMI and I get TV audio instead of Netflix. Sometimes, powering down everything works to restore the connection, but the issue soon returns. Any thoughts on this? — Larry Hochstetler