[survient]

Hey all, looking for suggestions on a new usb audio interface for desktop usage.
 
I currently have been running with a hifiman EF2A dac with 6J1P-EV Russian(Soviet) tubes for the past few years connected to a Linux workstation.
 
It's starting to show it's age with the TRS jack being a little spotty and some minor periodic hissing during playback that occurs from time to time that goes away when I replug the USB cable into the back. It's probably repairable but I imagine it's about time for an upgrade anyway.

I'm neutral about the tubes; I just bought the EF2A on a whim and figured why not.
 
For sound signature I usually go for flat and accurate. I'm currently using a Beyerdynamic DT-290 headset with a DM-290 mic that hooks up using a 1/4" TRS jack for the headphones and an XLR jack for the mic(the cable is modular).
 
My setup at the moment is a little complicated. The end goal is to be able to use the DT-290 with the workstation via USB, and be able to jack into an Avaya IP phone using an RJ11 to dual 1/8" TRS adapter(what a normal PC headset would use) plugged into the handset jack.
 
The way I have it configured right now is to use a Stereo 1/8" TRS to RCA adapter to connect the avaya phone to the EF2A's analog input, and have the USB connection plugged into the workstation. For the microphone I'm using a Behringer U‑Phoria UMC22 pre-amp/DAC which allows me to plug into the workstation via USB. To get the mic into the phone the UMC22 has an analog 1/4" TRS output that I'm running to a Behringer mx400 mixer/amp(4 channel mixer from another project), and then from there to the 1/8" TRS input on the phone handset adapter. From there I'm able to switch between the two sources using the switch on the EF2A.

Definitely a convoluted setup I'd like to simplify but that's where I'm at currently. I have the option of using a soft-phone but I prefer using the physical phone so a DAC with a switchable analog input would be preferred. Technically I can also set up the app on my phone(EC500) to receive calls and pair to my workstation via bluetooth(HFP), but I'd rather avoid that route.
 
If anyone has come across another device or setup that would be a better fit for what I'm trying to do I'm all ears. Thanks.

 

[obobskivich]

I think the EF2A is still made, so if you wanted to replace that box that's probably an option. As far as what you're doing overall, "DAC with an analog input" is kind of an oxymoron (since the point is a digital to analog converter). But I do understand that we live in the era of basically any box that fits into "headphone + computer" becomes a "DAC." My initial question is why don't you just use a 2 in/2out or 4in/4out (or some variation thereof) USB audio interface, and loop the phone through that. You'd have audio from the PC via the USB interface, and be able to mix the phone's level (both in and out) in real time along with the computer's "internal" audio (e.g. music, movies, whatever the heck you're getting out of the computer, sound-wise).

Basically what I'm imagining is [whatever audio interface] with 2ch output into the adapter for the phone input, and 2ch input for the phone output, and then hook up your headphones and mic to the other ports on said device.

So like say the Focusrite 2i2 - you'd only get mono out from the phone (hook it up to one of the front inputs), but I'm guessing that's all it really is anyways. And if not, just upgrade to an interface that can handle four incoming tracks so you've got one for the mic and two for the phone.

Depending on the computer you could probably do this with an internal card too, just have to make sure it has sufficient inputs (which are getting scarcer on newer hardware).

 

[survient]

I think the EF2A is still made, so if you wanted to replace that box that's probably an option. As far as what you're doing overall, "DAC with an analog input" is kind of an oxymoron (since the point is a digital to analog converter). But I do understand that we live in the era of basically any box that fits into "headphone + computer" becomes a "DAC." My initial question is why don't you just use a 2 in/2out or 4in/4out (or some variation thereof) USB audio interface, and loop the phone through that. You'd have audio from the PC via the USB interface, and be able to mix the phone's level (both in and out) in real time along with the computer's "internal" audio (e.g. music, movies, whatever the heck you're getting out of the computer, sound-wise).

Basically what I'm imagining is [whatever audio interface] with 2ch output into the adapter for the phone input, and 2ch input for the phone output, and then hook up your headphones and mic to the other ports on said device.

So like say the Focusrite 2i2 - you'd only get mono out from the phone (hook it up to one of the front inputs), but I'm guessing that's all it really is anyways. And if not, just upgrade to an interface that can handle four incoming tracks so you've got one for the mic and two for the phone.

Depending on the computer you could probably do this with an internal card too, just have to make sure it has sufficient inputs (which are getting scarcer on newer hardware).

 
Honestly the Focusrite Solo would work as far as input/outputs are concerned. My only hesitancy is that for power(along with the 2i2) it purely pulls from USB. I'm not sure that's going to be enough to drive the DT 290s, or supply a strong enough mic signal to the phone. Actually checking the Behringer UMC22 it seems to fill almost the same exact role as the Solo, and like I said right now I'm having to use the mx400 to boost the signal enough for the phone to pick it up(almost at max gain/volume).
 
A piece of audio hardware similar to these devices would probably work, I think I just need something with a little more "oomph".
 
Thanks for the input though.

 

[survient]

One problem I think I may run into with these usb audio interfaces is the inability to separate the line out and the headphone monitor. In order for the microphone output to make it's way into the phone through the line out, I have to enable "direct monitoring"(switch on the UMC22). If the headphones are plugged into the interface this means I'll hear the microphone at the same time. If I disable direct monitoring, then I no longer will hear the microphone but it also means the phone won't receive the microphone signal either.
 
If not for that issue I'm thinking the Tascam US-2x2 may work http://tascam.com/product/us-2x2/specifications/ it has the highest line out max output levels I've seen(+20dBu) of these types of interfaces. I just tried the DT290s on the phones jack of the UMC22 and it powered them just fine; I think it just wasn't designed to output that high of a line out signal which is why I'm having to use the MX400 which has a max output level of +16dBu in order to amplify the microphone signal high enough to get picked up by the phone.
 
So I guess what may be looking for is a usb audio interface or similar device that has separate switches for "direct monitoring" between the headphones and the line out, that way I can enable direct monitoring on the line out but disable it on the headphone output.

 

[survient]

Ok so I did some further digging into usb audio interfaces and I came across this one: https://www.native-instruments.com/en/products/komplete/audio-interfaces/komplete-audio-6/
 
This has a dedicated switch for which pair inputs it is set to monitor through the headphones. What I'm thinking here is I have the microphone hooked up to channel 1, then have the deskphone audio hooked up to channel 3/4. The headphones are set to monitor lines 3/4 so I'll hear the USB audio as well as the deskphone audio, but not the microphone. The line out for channels 1 and 2 will be hooked up to the deskphone so the microphone signal will make its way into the deskphone. The PC audio will also go out to the phone but I'm already dealing with that in my current setup; I just mute the PC audio when I get a call.
 
I *think* this might work, but if anybody has a better idea or guidance on this it would be appreciated. Also let me know if you've had positive/negative experiences with this interface. Thanks, and also thanks @obobskivich for pointing me in the right direction.

 

[obobskivich]

No idea about Native Instruments in terms of experience, but that looks like it'll work just fine for what you're wanting to do on paper.

 

[survient]

Wound up going with https://www.native-instruments.com/en/products/komplete/audio-interfaces/komplete-audio-6/ using jackd and it works great after getting jackd setup. Ironically had a more handy family member work on the EF2A and replace the tubes with different ones and it sounds amazing, especially on some grado PS500s.