So before buying I spent uncountable days/hours looking at reviews and watching a evenings of videos. On paper the 250mW x2 @ 300Ω seemed interesting over the 100mW x2 @ 300Ω on the MX3s, plus the lower noise and THD levels.
It was £200 on Amazon so I knew I could get it and return it if the amplification wasn't a marked improvement over the MX3s which already is an excellent amp for headphones and speakers, whether in low or high gain as there's no distortion that I could hear at any volume that wasn't genuinely uncomfortable.
I made some immediate observations that I did not like so much, too (noted below).
For ref, my HD650s are using stock (revised) pads which I replaced recently, the cable is a Custom Cans ultra-low capacitance Cardas one, not cheap but not super expensive either, I just wanted the lightest cable that I could choose my own colourway on. Far as I am concerned I'll have the 650s for life at this rate so may as well get a cable that is equally invisible on my head and high quality. Personally I don't rate the thick and heavy and long Sennheiser cable...
General observations
I'm connecting via USB to the PC and the MX3s is connected via optical for convenience as there's a weird bug with USB on the MX3s and my mobo combo whereby the audio stalls randomly, not often but maybe once a month, sometimes once a week etc and I knocked it down to my USB ports and some kind of compatibility with the MX3s. The sound between both USB and optical is identical though and the spec sheet is the same too so no real bother, convenience as I say.
Anyway....
- I like how on the MX3s to enter the custom menu you just put it into standby and hold the knob in until the menu appears. On the DX3 Pro+ you cannot do this, you literally have to unplug the DC power cord then hold the knob in, then plug the power in and only then will the menu appear.
- I also noticed that the lowest screen brightness on the DX3 Pro+ is a step brighter than the lowest on the MX3s, in order to match the DX3 Pro+, I have to put the MX3s in brightness level 2. At brightness 3 (the highest) both appear similar.
- I also noticed that the volume knob on the DX3 Pro+, whilst nice and clicky, misses an increment or two when adjusting the volume up, but not down. Here's an example.
- I don't use bluetooth on the MX3s so won't be using on this either, I wanted to go into the custom menu to turn it off, the manual says you can do this, it's the last option in the custom menu but in the latest firmware (1.25) it does not appear to exist so bluetooth is always there flashing if you cycle past it.
- I like the fact that the power brick isn't a brick but a wall wart, the plus points of DC-in... Shame it's an awkward 15v output though so finding a replacement if this ever fails may be tricky.
- Windows 11 defaults to 32-bit 48KHz, not sure why, if only Windows was this generous with Bluetooth headphones instead of picking SBC/AAC when you pair high-res headphones to the stock bluetooth stack (you can work around this using the Alternative A2DP driver which allows you to pick LDAC etc but it's not free). I set it to 24-bit 48KHz as most of my audio playback is in this config.
- You cannot set the volume display to % instead of dB. On the MX3s this is a toggle in the custom menu, it's missing on the DX3 Pro+.
- There are no EQ tone controls on the DX3 Pro+ like there is on the MX3s, more on this below.
- I like that the DX has relays when you switch sources and power on/off the unit. The MX3s does not and you get a soft pop from the speakers when it goes on/off etc. I like the physical sound of clicking relays too.
- DX3 Pro+ gets warmer than the MX3s, glad I kept the stack with the DX on top lol.
The sound
I have a few songs that I always like to test with speakers and headphones to make sure each side is still going strong and not rattling or something.
- Getting Older by Billie Ellish (the first 10 seconds) - At high volume is pristine on both amps. No distortion at all other than the slight imperfections in the mastering of the song itself which is audible on the right channel, this can be heard even on the speakers so it's definitely the song.
- Regular Pleasures by Patricia Barber - A superb song for bass strings in the central background with supporting instruments that come and go in sublime stereo imaging and soundstage. At 2:10 into the song a trumpet comes in whilst the other instruments remain active, the trumpet is high frequency and her vocals are also coming in, every single detail is perfectly preserved all whilst the HD650s relay a level of sub-bass that you wouldn't expect if you only knew of the HD650 from online comments where people state it has not enough bass. Yes it does, it has "honest" bass., not too much, not too little, just the right amount to feel authentic and "live". Even at -5dB on the volume with the DX3 Pro+ there was no sharpness or sibilance, and this was at low gain which is +6dB (high gain is +19dB btw).
- I can't Go For That ((No Can Do) by Daryl Hall & John Oates - A song that basically has no bass notes, it focuses almost exclusively on vocals imaging and electronic instruments. This song really shows of the mids on the HD650 and is the song that shows difference between both amps. The DX3 Pro+ has more refined midrange listening to this song, the vocals especially and how it images the mixture of instruments and vocals that play throughout.
- Why So Serious by Hans Zimmer - Are you even a human being from the 21st century if you don't know this instrumental? The rumble that comes in from 3:25, at -7dB on the DX3 Pro+ reverbs each ear individually whilst the little ticks in the lower right just behind my head get louder and central rear behind my head the background clatter softly fades. On the MX3s soundstage and imaging sound identical but the DX3 Pro+ just has more refined midrange I feel, there's more punch if that makes sense? The low bass extension is also more refined.
- Sadie Wants The Night by Pure Obsessions & Red Nights - Again more emphasis on midrange with the DX, and actually the soundstage is slightly wider but not by a huge amount. The MX3s plays this song amazingly and it's why I added it to my demos playlist a while ago after hearing it for the first time on the MX. The DX is just more refined playing this song too.
- I Need A Dollar (Live In Studio) by Aloe Blacc - There's electric guitar on the left channel on this song that on the MX3s sound excellent but it feels like it's fighting for airtime with Aloe's voice at times. On the DX3 Pro+ this feels like it's been ironed out thanks to the emphasis on refined mids and imagine/soundstage.
- CYBERPSYCHO by MAGNAVOLT - One of the OST tracks from Cyberpunk 2077. Bass-heavy and lots of highs and lows with the mids taking a bit of a step back through the whole song. On the MX3s at -5dB I can tell that this volume is too high which would fatigue my ears due to the heavy use of high frequencies in this track. However, on the DX3 Pro+ I had the volume at -9dB to get the same loudness and the highs didn't feel as in my face so no sense of potential fatigue. Once again, refined on the DX. Interestingly on this track I found the MX3s at lower volume levels like -30dB controls the song better than the DX does, maybe it's because of the tone control on the MX but there's slightly tighter bass on the MX at lower volumes playing this than on the DX.
I found that the volume level between both is different, which is expected given the different HP output power levels. At -7dB on the DX3 Pro+ I had to put the MX3s at -5dB, and even then the DX was slightly louder and the mid-range especially vocals feel more prominent. I do have the MX3s slightly EQd onboard too, with +3 on treble and +2 on bass to my preference.
Since the DX3 Pro+ has no tone controls I was expecting this to be an issue, but nope, the sound is actually slightly warmer still with what seems like a bit more focus on the bass extension.
So what's the gist, is there a difference between both headphones outputs between both amps? Yes. DX is just more refined, has more volume, but with some songs does better at higher volume than lower volume, which is probably what most will be doing anyway otherwise why put on headphones
I'll be keeping it stacked with the MX3s!
