The HD6XX (HD650) is one of those headphones that has near unlimited potential with scaling, put it on a Schiit stack and it will get beat by most headphones out there (when plugged into the same amp), put it on a TOTL amp and the reverse happens. This is the reason I like it so much, it’s extremely transparent and responds very well to gear changes. After 20 years and 6-figures spending on this hobby, I have not found another headphone I enjoy more than my HD6XX, some came very close to the same level of enjoyment but are not categorically better.
Rewind 7 years, I flew to Singapore’s Adelphi plaza to audition some speakers, after three days at Adelphi I was feeling bored and decided to visit the headphone shop by the building’s entrance, at the time they had a Schiit Lyr and two headphones on display, an Audeze LCD-2 (the original, now rebranded LCD-2C) and the HD650, I already had the LCD-2 – so I listened to the HD650 and it immediately blew me away, it was incredibly coherent, well balanced, the soundstage was intimate but not so narrow as people made it out to be, and the midrange was magical to say the least.
I did not buy it immediately, because I attributed my initial listening experience as “new toy” syndrome. Besides, at home I had the HD800 and LCD-2 to entertain me, the HD650 couldn’t possibly be better (could it?), and I also had the HD600 which was supposed to be almost identical to the 650 (it isn’t, but that’s what I believed at the time). I forgot about the HD650 for a period until a few years later, Massdrop listed the HD6XX and I thought – why not? – and since then the HD6XX has been my reference headphone.
As with any audiophile, I was struck with upgraditis not long after but I have not found anything categorically better. The HD6XX does have a few downsides that bothers me, such as the slow decay, while it makes acoustical music (what I listen to most) more romantic, it isn’t best at showing all the details. I decided to venture out and audition all the heavy hitters, taking along my Metrum Octave 2 and Audiophilleo PurePower (because they are so transportable). Here were my thoughts:
Focal Utopia vs HD6XX, on Moon 430HA
I’ve heard so much about the Focal Utopia and how Tyll uses it with the Moon 430HA so that’s what I decided to compare with. The Utopia was the more transparent headphone, and I felt the HD6XX kept up quite well and was only behind due to their slow decay. The soundstage on the Utopia was not huge, it was intimate like on the HD6XX, only slightly larger. In terms of tonal colour, the Utopia had the upper hand. Where the HD6XX had the upper hand was tonal linearity, more meat on the bones, and a less fatiguing sound. As someone who prefers tonal linearity over tonal colour and dark sounding over bright sounding, I felt the HD6XX was the better headphone overall.
Hifiman Susvara vs HD6XX, on ifi Pro iCan
The ifi Pro iCan had just been released and was the flavour of the month. In hindsight, I felt the ifi Pro iCan probably wasn’t the best choice for the comparison, as it had bottlenecked both headphones. I know this because both headphones sounded more similar than different and the HD6XX certainly didn’t sound their best. What I noticed was the Susvara had better macro dynamics and a small increase to soundstage width, about the same as going from the HD6XX to the Utopia, but I suspect there will be bigger improvements with a better amp. I need to do another comparison, but what this tells me is the HD6XX and Susvara stands toe-to-toe with mid tier amps.
Sennheiser HD800S vs HD6XX, on Woo Audio WA6-SE
When I previously had the HD800, I had it on the WA6-SE, so I thought the HD800S would sound best with the same tube amp. Just like the HD800 the ‘S’ edition had a massive soundstage, impossible to believe, and detracted from the listening experience. The soundstage was wide but not particularly deep, while on the HD6XX the soundstage had a good ratio of width and depth, every time I put the HD6XX on a good tube amp I marvel at the soundstage depth this headphone is capable of. The bass is lean compared to the HD6XX but makes it up in overall speed, the treble is still fatiguing especially compared to the gentle and lush HD6XX. Like the Utopia, it is thin sounding compared to the HD6XX, the timbral harmonics are crystal clear on the HD800S while they are more accurate on the HD6XX and carries believable nuance. Overall, like its predecessor, the sound coming out of the HD800S does not sound real.
So, what I would consider as a good alternative to the HD6XX? The now discontinued Hifiman He1000v2 (or the SE if you want better all-round performance but a recessed midrange). When I listened to this headphone against the HD6XX for the first time on a Bryston BHA-1 I thought, “yeah, this is it”, it's probably the closest I'll get in today's headphone technologies. It’s a completely different sounding headphone, it’s fast, has an airier soundstage, more neutral tonal colour, better extension and has most of the great characteristics of the HD6XX like linearity, body, harmonic richness and great slam. Only falls a bit short on midrange magic but I could live with that. For Massdrop users, the Hifiman Edition XX might be very close too, and I plan to buy a pair eventually.
Maybe the Susvara is even better on a good amp, but it’s 3000% more expensive than the HD6XX, and would push my reference amp to its limits, and I’d rather not use my 2kWh/ch monoblocks to drive a pair of headphones. Although I’m the type that sees audio expenses as a matter of “when” not “if”, I still prefer good value than impractical gear, and to me, or anyone with TOTL gear, the HD6XX is the pinnacle of great value with performance to match.