Headphones

IME the 6x0's do exceptionally well on the right source gear. If you're planning on upgrading anyway for the Sundaras, it might be worth holding on to until then to try on the new source gear.

That said, I can't think of any amps that paired nicely with it that isn't just as much if not more than the cost of a 6xx. I haven't tried 6x0's on too many things but the least expensive one I really liked was on the Jot 2's balanced out.

The HD600 line tends to be known for lack of bass presence, particularly with subbass and overall quantity. However, if the old K3 is not a fully balanced DAC/amp design, then the balanced output might be altering the sound in a negative way. I've found that the balanced from my BTR5 starts to distort the bass considerably (especially on my MDR-Z1Rs), whereas the unbalanced (and other amps I have used) are completely fine and distortion-free through their intended outputs.

I wasn’t into the 6XX’s until I tried them on the Schiit Vali+. Hybrid tube amp. No EQ. Let the tube do its thing with them. Also the HD 600 on the Vali+ sound amazing to me too.

Within every hobby, it seems, there is always a standard item most people gravitate towards. It's usually fine, and at a good price to performance level, but not exceptional or especially interesting.

You have described my audio journey. I don’t have the 6xx but I have the Akg, 599 and 598. Heck I almost bought some 6xx’s used on marketplace🤣. Will also be reading the comments with as much interest as OP.

Maybe the 600 will be my next step. I do enjoy the Sennheiser ideal of having nice mids. Some people don’t like the high bass boost but I enjoy it. Hifiman’s QC is too scary for me.

sounds like the sundaras are a better choice, that is if you can get one b stock/open box and not falling apart immediately

The HD6XX is a very chill/smooth sounding headphone, and you're coming from the HD 599 which was a pretty much oppossite lol

The bass is very pillowy and weird, and it's just not clear. The treble and mids sound fine. I've narrowed it down to 2 possible reasons.

That sounds about similar to my experience with using the HD650 at least. However, I found the treble more subdued (probably cause the ones I got had already well used pads and aren't close to new). Bass doesn't have a lot of excursion and doesn't go below I believe 75 Hz or something lower if my memory serves me right. These aren't really known for having great bass impact and quality, especially if you're listening to a lot of modern music that uses a lot of synthesized bass sounds.

Either I got a bad unit (I have yet to hear another unit, so it's highly likely that it's not), or my source is the issue

Kinda doubt you'd get a bad unit. It's just the tuning is what you're not used to. I haven't tried the two headphones you mentioned, but it just seems based on your experience that you're well used to a sound signature that has better bass extension and the HD650/6XX just doesn't have that.

If you wanted better bass quality, you could probably try the other offerings such as the Focal line up or even Beyerdynamic (but would suggest EQ'ing out the treble region that is prominent).

I got some 6xx's I only picked up since finally a 600 series phone that is priced where it should be: around 190.

They're fine but they're nothing special. You can outperform them with he400i that could be had for 90 bucks brand new from hifiman and they're far more comfortable to boot.

I agree.

I have HD6XX. The mid range is really nice. But the presentation is so narrow and intimate there is really no wow factor with this headphone.

A Focal Elegia, priced similarly, will wow far more imo, with much greater detail and soundstage, but a less Harman tuned FR.

I would not get the sundara headphones if you think the 6xx are lacking bass. Sundara has almost no bass. 6xx are entry level. Lower your expectations. The reason why the 6xx are considered so good is because it is often the first pair of headphones that people are introduced too.

I would not buy anything in the 300 dollar range if i were you. I would buy an amp as it seems you have a dac. I would than look for a pair of headphones you could save for for like a year or something.

Coming from anything that has extended treble and/or deep reaching bass, the 6XX can sound like nothing. Either you love it or you hate it.

I noticed this after I got my Aful Performer 5, since I wanted to try one of the better IEMs. My 6XX has a mod for more bass and I use a tube amp, but honestly, the bass is not its strength. Then there's the dark tonality. If you come from anything that has extended treble the 6XX will sound like you have a towel wrapped around your head and the headphones on top of that.

But here is the thing: This headphone is just so relaxing. It won't blow you away, but it will just always be your safespot. You can listen to anything without fatigue. Give me any other headphone and I will be absolutely exhausted after 2 hours. That doesn't happen with my 6XX.

I doubt your amp is the issue, it's just the tonality of the 6X0 series. But heck, if there's somehing like a 6XX with deep reaching subbass + a little better technicalities then it's a nobrainer 10/10 headphone imo.

Massdrop tends to ruin everything they touch, I would avoid them like the plague.

They are laidback headphones so that kind of makes sense to me. I really enjoy mine though. I also have a pair of he400i planar magnetic headphones which are very energetic and exciting, but I enjoy the more relaxed sound of the hd6xx as a compliment to them.