When I was first checking out the Sound Blasterx G6 headphone amp and DAC combo, I saw several people throwing shade at it in audio forums with statements like: “They lost me at USB-powered.”
As if the 2.5-3.75W that the standard USB port puts out couldn’t possibly be strong enough to drive a pair of headphones (5V @ 500-750 milliamps).
I raised an eyebrow, thinking that through for a moment. Even if we account for power headroom to run the actual device, the parts that have nothing to do with the amp like the lights and other circuitry, it seems far-fetched to think that’d be more than a half a watt.
After all, as lights go, half a watt to a watt is far brighter than what a little sound card puts out on your desk.
That would mean that even a 50% efficient class B amp should be able to put out close to 500 mW on low impedance headphones. And on higher impedance cans, hopefully around 100mw.
Turns out the G6 measure close to 85 mW output on 300 ohm headphones, which is a little lower than I expected but still ample.
For a point of reference, most headphone specs list their sensitivity rating as a decibel number at 1mW. My Beyerdynamic DT 1990 show as 102 dB/1mW, meaning it takes only 1mW to produce 102 dB of sound (generally in the midrange).
A general rule audio enthisiasts have is that you should be able to hit 110 dB. Not that you want music that loud in any sustained way, but when your amp can get you that loud it ensures that transient peaks like big drum hits and cymbal crashes have impact. Peak sounds can often be 10-20 dB louder than everything else, so having enough amp to reach 110 dB means your average volume can reach 80 dB (a pretty loud listening volume as it is) and still have the headroom for the peaks.
But following this rule, if we trust the manufacturer’s specs on headphones like the DT 1990 that claim to start at 102dB with 1mW, that means getting to 105dB happens at 2mW, 108dB at 4mW, and 110dB roughly around 8mW.
Since the Sound Blaster G6 was measured to output 85mW at 300 ohms, we can safely say there’s plenty of power unless we’re talking low-sensitivity headphones (under 96 dB/1mW) or extremely high impedance headphones (over 300 ohms).
In my experience, I generally only need 15-30% volume level on the G6’s high-gain mode for comfortable listening with my DT 1990 @ 250 ohms. I think that impedance is a pretty good representation of what it’s like to drive typical high-impedance headphones.
(Headphones over 300 ohms seem fairly rare, anyway.)
So from both my practical experience and what others’ technical testing suggests, the G6 is a pretty capable amp for most headphones. I have plenty of volume headroom and at no point am I wishing I had more power.
Sure, other headphone amps by companies like Schiit and Burson have output power reaching ~2W. But I feel like for the average audio enthusiast — or dare I say it, audiophile — the amount of power the G6 delivers is plenty.
Same thoughts for sound quality.
Many people dislike all the audio fluff settings that come with a Sound Blaster card and I largely agree. But you can elect not to use them, and then the G6 becomes a fairly strong headphone amp with a very respectable DAC.
Maybe Creative have put out enough overhyped products that people are leery of them, and not willing to accept that any modern amp made by them could be any good. But with this one, I think they nailed with with a lot of value for the money.
Other Options Like The Fiio Q11 DAC/Headphone Amp
The Fiio Q11 is a battery powered headphone amp that can take a USB-C input for its DAC, and output 165 mW at 32 ohms, or 19 mW at 300 ohms.
I’ve calculated that with my headphones’ 250 ohms this amp can produce 21.16 mW in the unbalanced output.
It’s not as strong as the Sound Blaster G6, but for efficient headphones over 100 dB/1mW it’s still stout enough.
I generally use them at 40-55% volume for a listening volume (on modern music) that’s engaged and more than casual, but not quite the max comfortable I could take. It’s definitely higher on the volume dial than the G6, but leaves enough headroom that I’m not worried about it.