Thank you for your help. Yes the volume is maxed out on everything, from the source app to the OS. Now that I have the DFR (arrived just this afternoon), I've noticed huge improvements, but not with the Beyerdynamics. I also have a pair of Sennheiser HD 700s with me, and while I know these are 150 Ohms, the improvements are night and day.
I guess my questions that now remain are: were the Beyers that hard to drive? You mention the Asgard was lacking at that impedance, as opposed to 190mW max output at 600Ohms, what would be sufficient to drive these DT880s?
190mW isn't insufficient for 600ohms, it's what it produces at 600ohms. What that is insufficient for is the 96dB/1mW sensitivity of the Beyer, which doesn't improve with the 600ohm impedance. All that does is reduce distortion (and noise) with high output impedance circuits driving it, like high power consoles in studios that have a lot more voltage but have low current delivery and run at Class A/B instead of the high waste heat, ultra low THD+N on hifi amps like the Asgard. Think of the comparison like why home speaker amps can be 15watt per channel Pass Labs pure Class A ultra low noise amps while pro amps are Class G 300wpc amps.
On its own 190mW
should be sufficient,
but the thing is, there's still gain. It's like having a good enough turbo engine on a light enough car, but the transmission has the wrong gear ratios. A lower voltage to noise ratio signal input into that amp is like using regular fuel on, say, a current gen Honda Civic Type R's 1.5L turbo engine. Just because Regular works fine on a 2.4L Accord engine doesn't mean a smaller, highly tuned engine wouldn't benefit from Premium gas.
If you had the 250ohm version the Asgard would produce more power, and likely the gain would be sufficient, but there's still the noise that's coming through from the source signal. There's still the question of whether it's just the Asgard struggling with the 600ohm headphone that the noise benefits are overturned or the noise is coming from the rest of the signal chain. If there's noise in your other lower impedance headphones, then it's likely the signal upstream from the Asgard, up to your power lines (which is why I said test your gear at another location, albeit it can't be something like a noisy coffee shop where you might not hear the noise). If not, then the problem is in the interaction between the Asgard and the 600ohm headphone, and at this point you have to decide whether you want to keep a 600ohm headphone and get a more powerful amp that won't have trouble with lower impedance headphones (more so if the sensitivity is markedly lower) or use an amp optimized for voltage but with crap current delivery into low impedance, low sensitivity headphones, like an OTL tube amplifier.
While I have your attention, I hope you don't mind I ask you a few more.
You mention I'm not using a 'plain 2v output', is that achievable with a MacBook with only usb connection?
Yes. It depends on the DAC's circuit. If it's not dependent on USB power or has a separate USB power port from the signal port, then there's a higher chance it's not limited to motherboard 500mA and thus usually spec-ed for 2V output, and
probably also much lower noise.
If I understand correctly, perhaps a dedicated DAC / non-integrated amp would be better? I assumed the DFR would act solely as a DAC and the Mac would simply pass the digital signal to it, untouched.
Yes and No.
Yes, the Mac does pass the digital signal "untouched" unless you use some kind of software.
No, having an amp and DAC integrated into one chassis sharing the same power supply is not always bad. You can use something like a Burson Conductor or Violectric V280 and these can spit out a lot of power and current better than some dedicated amps, but then again that's a $2,000 DAC-HPamp-Preamp unit. Your problem there is that the DFR's DAC and HPamp circuits are running off USB power, so using it as a headphone amp isn't ideal for anything with very high impedance (requires voltage) or low impedance, low sensitivty (requires power and current), while the circuit might not be the cleanest DAC output into a headphone amp if the signal passes through the HPamp output stage anyway since amplification circuits inevitably add noise. That's why stacking amps where one amp adds noise and the second amp amplifies the entire signal including the noise isn't ideal - amps for hifi use don't exactly work like anime robots connecting two beam canons in series to increase range or have enough power to punch all the way through a space navy capital ship with an anti-beam coating/shield.
Power supply is another concern here on my desk. There are lots of power hungry devices ticking away while I listen. Should this setup be isolated, or at the very least connected to a conditioned or clean power source? I wasn't aware this could be a big enough factor.
It's not simply how much power all those other things near it need from the wall so long as the wall power can deliver that power, whether you have a voltage regulator/UPS or not. Someone with an SFF computer with an APU or a NUC (Mac Mini in Apple terms) can still get a lot of noise into audio components.
You can try a noise isolation device but remember that this isn't always a guarantee that it would eliminate all the noise, regardless of whether some of the noise is coming from one of the audio components or the wall. This is why I'd save it for last and try to eliminate it or see how much it actually contributes vs one of the audio components by testing your gear elsewhere, considering this isn't a speaker system that for example all needs to get tested at a dedicated audio room like a hifi dealer's showroom just to see if the house/flat is the problem. I mean I'd still hook up my audio components to a separate line conditioner than the voltage regulator the computer is hooked up to, with both connected to separate power outlets,
but for starters I already have a Meier Cantate.2 that can use its internal USB input from an Android on Airplane Mode, and with no music playing and the volume cranked up, there's absolutely zero noise; ie, this is a
For my personal taste, the Beyers are too bright and from what I read some others feel the same way (mentioning a 'V' shaped sound, even when properly driven). My last question for this setup, is what headphones (assuming I work out the noise issues) would you recommend? I have experience with Sennheisers, and the HD600s look like a good match, but as always your wisdom is appreciated.
Is there noise when using the lower impedance headphones? If there's none on the DFR driving them, then it's probably not the Macbook or the power line. Then it's either you replace the Asgard or the DT880, plus add a DAC to work with whatever amp you'll end up using.
The DAC itself is rated for 2.1 V out, what am I missing here?