[Tim D]

It can act like a tube processor...I haven't had much experience with tube equipment...but I'm not going to assume this tube processor will demonstrate the sound qualities of all other tube equipment. It certainly is fun to play with however regardless, but since I primarily use it as DAC only I removed the tube for less power consumption and heat.

The digital output being hot or not has nothing to do with it...the analog outputs of the D/IO is HOT. Out of my CDP the volume is extremely loud. I wouldn't hook it up to any headphone I value for very long. For example my Ety's can support up to 3.0 V RMS according to specs. And the D/IO can output more than double that. I don't know if I can vouch for safety, I just know that it is a DAC, and a somewhat unorthodox DAC at that (being prosumer usage)...so driving a prosumer DAC as a consumer headphone amp is just not the best thing to do. Also digital attenuation is BAD, you want your soundcard at unity gain for digital volume and an analog volume control.

The noise issue isn't bad...I'm just saying that as a pure DAC the D/IO's performance is much much better. As a tube AD/DA processor the sound is still reasonably clean...there are plenty of portable CD players or other equipment I could imagine to sound worse or more noisy. I'm not saying that hooked up as a AD/DA processor it will introduce noise that is easy to hear...on the contrary it might be difficult to most to discern that another AD/DA process has been added to the output...on the otherhand to the perfectionist, yes it can be discernably worse.

Don't worry, at its price the D/IO is still a great product...just don't expect it to be a headphone amp as well as a great DAC. Again wheter or not the D/IO can easily be converted to headphone amp usage is another matter...the first thing however would be good quality attenuation control. Than figuring out of it gives enough current without croaking.

 

[ck42]

Tim:

Thanks for the clarification. Ja, I already know about the HOT 7V outputs on the analog output side of the ART. That's an issue I going to have to address. I'm hoping there is a GOOD way to bring it down w/o degrading the analog performance. Seems like the gain on the opamp in the ART could be tweaked to bring the output voltage down or something like that.

The idea of having the ART be an amp is interesting but I'm not really going to try and make that work...it was just curiosity.

Plans are to run the ART to a CMoy amp I'm going to be building shortly.

Peace.

 

[Tim D]

Cool...also keep in mind that the szekeres might be a nice DIY amp because it has no gain...but the hot output of the D/IO makes it so you don't need any additional gain stage.

 

[Hirsch]

Many preamps and headphone amps can handle the hot output of the DI/O. If yours can't, you'll hear it. If the sound is clean, your headphone amp isn't taking concealed damage. Check out the posts in "Digital Drive" at www.audioasylum.com to find out more about the DI/O than you'd ever want to know.

Converting the DI/O to a headphone amp is simplicity itself. All you need is an adapter that converts a stereo phone jack to two mono phone plugs. Or, if you already have RCA to phone adapters for the DI/O, you can covert the stereo jack to RCA plugs (this is what I did to test the idea for my post above). Zero gain still puts a signal at the headphone, but it's low enough so that additional gain was needed to drive HD560II's at comfortable listening levels. I have absolutely no idea what the initial volume level would be with a lower impedence can.

The ART was designed to act as a signal processor. As a "tube" preamp, it's sound is variable...the user can adjust the contribution of the tube. Different manipulations of the "input gain" and "tube warmth" controls produce different sounds. So, the ART does not have a "sound" of its own, but rather a range.

There are a number of ways to alter the output gain. The easiest is an outboard attenuator. However, the three headphone amps I've used the DI/O with (Grado RA-1, Creek OBH-11se, and X-Can v2) do not require attenuators, just a light hand on the volume control.

 

[Tim D]

I was just making a point that in most non-computer audio systems, where the line-out/digital-out is not variable, it is at unity gain. Unity gain on many many soundcards is usually maxed digital volume in mixer control panels. If you lower the mixer settings on your software mixer or app mixer, than yes the sound is more managable. This mixer also is usually a digital attenuation however which means loss of signal quality.

Also again the unit has an output impedance of 220, so if you really want to use it as a headphone amp than it would be safest to have something higher in impedance. Supplying a hot output to some headphone amp is not bad...but driving equipment designed as a DAC as a headphone amp can put strain on some components in the form of heat if it is asked to supply more current than it is spec'd to. On the otherhand it is a proaudio unit with heatsinked components that is designed to deal with tube heat and somewhat limited venting. But, tube heat, limited venting, and driving it as a headphone amp all at the same time may push it. I am just following the better be safe than sorry motto.

I would imagine that headphones near 220 or so will be loud because a matched impedance will maximize power transfer. Lower impedances might not even work, if it doesn't than it could be a sign that it is drawing too much current and overworking opamps. So I suppose old fashioned studio monitors or other phones with 600 ohms are "safer" than other phones in this usage. I wouldn't exactly call its conversion into a headphone amp as trivial, since burning out the unit due to a bad configuration can be really trivial as well.