[miwo76]

I'm beginning to explore this interesting world of head-fi and have some newbie questions to ask the experts here.  I have a couple of headphones: the ATH-M50 and AKG K702.

I have an Audioengine D1 DAC/amp that I would like to feed into a headphone tube ampliflier, like the Little Dot MkIII.  The source files would originate from a computer into the D1 then I would connect the RCA outputs of the D1 to the RAC inputs of the Little Dot MkIII.  I don't currently own a tube amp, just planning ahead.
 
Since the D1 is a combined DAC/Amp, there's a volume dial (i.e. pot. dial) that is used to control volume when it is used alone.
 
If I were to connect the D1 to the Little Dot MkIII, where would I set the volume dial on the D1?  I assume it has to be turned above the minimum setting or no signal would be sent to the tube amp where I plan to connect my headphones and use the tube amp to control the volume.  As a corollary, could the volume setting on the D1 impact the quality of the sound coming out of the tube amp?

Thanks in advance!

 

[PurpleAngel]

I would think the best thing to do is turn up the volume control (75%-100%) on the D1 and just use the new amplifier's (LD MKIII) volume knob to control the loudness.
(Also set the computer's volume control up high)

 

[miwo76]

Thanks for the feedback!  I'll give that a try when I end up getting a desktop tube amp.

 

[yifu]

Don't worry. Daisychaining is only a problem for multiple very powerful speaker amps that are connected in a row at close to full volume, for example a pre-amp to another tube pre-amp to a power amp etc. And even then you are more likely to get distortion and lots of heat rather than it blowing up. With headphone amps there is no risk in damaging anything.
 
I'm not familiar with the the D1's topography but the RCA outputs in most DACs are 2V redbook straight from the DAC itself so the only way to adjust volume is from your operating system. (i.e. adjusting the volume knob will do nothing to the RCA output). That is a bad idea because when you reduce the volume of a DAC with a computer, you are reducing bit depth so a 24bit DAC suddenly becomes a 16bit and so on. Without getting too in depth, a 6dB attenuation using software volume control reduces bit depth by 1. 
 
With that said, if the D1 is one of the few weird DACs where the volume control actually controls the RCA output, make sure that it's set above 50% but less than 100% to reduce the chance of it clipping.

 

[miwo76]

Thanks yifu!

Much obliged for your articulate reply!  I think I learned 7 things in your reply.  Very, very useful learning and areas for future review.
 
1. Daisychaining of speaker amps
2. Safety of headphone amps in a daisychain
3. DAC 2V - in some DACs volume can only be adjusted by the OS
4. DAC volume adjustment via RCA
5. Change in bit depth (!!)
6. Some DACs allow volume control of the RCA output
7. Is the D1 a weird DAC that allows volume control of the RCA output via volume knob?

This post got me to look for the answer to point #7:  (short answer - YES!)
 
http://audioengineusa.com/Store/audioengine-d1-faq
 
Thanks again - fantastic reply in an interwebs forum!

 

[yifu]

DAC outputs are almost always line level, it's strange that Audioengine engineers designed a variable RCA output. In that case you should keep the RCA out as close to line level as possible, which could be anywhere from 50% to 90% volume. I'm guessing a 70% volume should be enough.