Beginning of a new journey...

I had never been a headphone guy, up until very recently. My main rig in my home office is built around Harbeth P3esr, Rogue Audio Cronus Magnum II, Cambridge Audio Azur 851D, and Bluesound Node 2i. I'm extremely satisfied with the performance of this system, and cannot ever imagine parting ways with the P3esr's. They tick all the right boxes for me.

Having said that, my headphone journey started with my wife buying me a Bose Soundlink pair of headphones about a month ago. I put those on, and the first word that came to mind was 'meh'. I tried them with and without amplification, but the result was always the same. Meh! I concluded that maybe headphones were not for me. But then a friend of mine told me that Mass Drop (now just Drop) were running a special on the Sennheiser HD6XX headphones. With the first-timer discount, and free shipping, the cans were going to run me $175 + tax. I figured why not. I am in love with the Harbeth midrange and smooth sound, so 6XX's sounded like the right choice.

Now, I also have a Naim Unituque (V1) that was in my system before I upgraded to the Cronus Magnum. The display light had started to fade and eventually went out completely. So much for Naim quality! Anyways, I was hoping that the Naim would be a good match for the HD6XX's. But nope! Not at all. The sound was anemic, slightly better than running them straight from my iPhone, but not that much better. The bass was almost non-existent. I guess headphone amplification was an afterthought on the Unitiqute. I wasn't sure if it were the 6XX's, or just that the synergy with Naim was not optimal.

On a whim, I hooked the cans to the Cronus Magnum's headphone out, and immediately they came alive. The bass was much tighter, the midrange, vocals, treble -- everything was noticeably better. I can see why these headphones have achieved such a legendary status in the world of affordable hifi equipment. They definitely scale with better equipment, unlike the Bose. So now, I need some advice regarding a good headphone amp. Given the limited room on my desk, I would prefer something with a smaller form factor, and a single box solution with preamp/amp/dac. It will be a bonus if the unit can have a built in streamer, but not a must. I want to stay between $500-800, new or used. I'm sensitive to high frequencies, so tubes will be my preference but don't want to rule out smooth sounding SS amps.

Any advise is greatly appreciated!
Most headphone access plugs are cheap/poorly designed op amps.  To get the most out of need a dedicated amp.
Most headphone access plugs are cheap/poorly designed op amps. To get the most out of need a dedicated amp.
Pretty sure he was asking about getting a dedicated amp.

I don’t have a specific recommendation as most of my headphone amps are out of that price range, but Drop has a number of headphone amps under $1K that come up.

Head-fi is a good resource for reviews as is innerfidelity. I’ve heard a lot of good things about Woo Audio’s tubed headphone amps, but not sure if they have anything in your budget.

If you’re patient, you might pick up a used Auralic Taurus in your budget range, that’s a great amp (not tubed though), but very smooth, detailed and just a little on the warm side.

Recently I read some reviews of the Cavalli CTH hybrid amp on Drop that seems to synergize particularly well with the HD6XX ‘phones. It’s only $175 but may be all you need to make your Senns really sing. The Schiit Vali 2 is another good option but is probably a little more on the neutral or less warm side versus the CTH. Hope this helps, and best of luck in your continuing journey. .
Great suggestions. The Auralic Taurus sounds very promising. I see a used one on this site for a little over my range, but might be worth a try. I checked the drop website for amps/dacs but it seems that anything that catches my interest is sold out/through and won’t be available for a few months.

There have been a few updates since I created this thread. I ended up ordering the Hifiman Ananda’s from Amazon (arriving this Friday). Of course they are three times the price of the HD6XX but I want to see if the price difference is worth it. I will A/B the two for a week or so and then make a call as to which one to keep. Supposedly, the Anandas are an easier drive, so they might work with the Naim unit.

Another option is to use the Naim as a DAC only option, and hook it up to a purpose built headphone amp like the Cavalli CTH hybrid.

The HD6XX are surprisingly good headphones at their price point.  They are probably the most comfortable headphones I own and they sound really good.  I have better sounding headphones, but they are many times the price of the HD6XX.  They definitely benefit from a good headphone amp.  There are also a lot of mods available for them - cables, earpads, etc.  I don't remember which ones I got, but I put some thicker earpads on and it increased the comfort level.  
@big_greg: Couldn't agree with you more. I've been listening to the HD6XXs for the last two days, and I'm blown away by the performance. In comparison, the Bose Soundlink retails for $230, and IMO there simply is no comparison. The Senns punch way, way above their price point. There have been so many wow moments, so many nuances in familiar music that I never knew existed. It's easy to see why these phones have so many admirers. 

So far I'm really enjoying the presentation, but a few things that I wish these cans had in a higher degree of abundance are more meat in the bass department, a wider soundstage, and maybe a bit more authority and heft. Otherwise, midrange, vocals, especially vocals, instrument separation and imaging are outstanding. Now since these are my first quality headphones I don't really have a reference point, so take it with a grain of salt. Once I get the Ananda's I will run both headphones through the paces and make a decision. Anandas have some big shoes to fill in.

Doing the same... while my wife and daughter highjack the tv/stereo, I enjoy my cans on my ears. 
So far, I have senneheiser 598 open-back, and Sony 7506 closed-back, alternating depending on mood and music.
I am using a motorola cellphone and tidal Master and hifi quality as a source, but I'll make this better with a schiit vali2 by the end of week.  
I'll just have to find the right tubes for it...
I'll just have to find the right tubes for it
How do you know it doesn't already have the right tube if you don't even have it yet?

I haven't heard it either so I could be misjudging the Vali because of its low price, but I wouldn't spend a lot of money on tubes on something that inexpensive. You could easily spend more than the amp cost on tubes and still have a pretty mediocre amp. What do I know though, there are 359 pages on head-fi about tube rolling in that amp so a lot of people have found it worthwhile. I owned a Mjolnir for a while, so I do have experience with their headphone amps. 

If you're on a budget, consider saving up for something better if it doesn't tickle your fancy instead of throwing a bunch of tubes at it to see what sticks. 
@chrisr Please do let us know your impressions of the Schiit Vali 2. I'll be getting the Anandas tomorrow. Once I figure out which headphones I'm keeping (HD66x or Ananda), the next step will be a suitable dac/amp. 
It's OK to have more than one pair of headphones!  You may find that the Ananda sound better, but maybe the HD6XX are more comfortable, or that one does better with certain types of music.  Having a bunch of different headphones is like having many different pairs of speakers, without taking up all the space.  I have 11 sets of headphones (which I admit is ridiculous) and they all sound different and all have different strengths and weaknesses.
Two nights ago, I was listening to some old headphones with a new set up. An old track came on, and the first couple of notes, then I what sounded like furniture creaking behind me, which was impossible. I restarted the song, and heard it again. Something that in 30 years I’ve never heard in this track.

The headphones? Nad HP50, considered decent in a sea of decent cans. The headphone amp, a Schiit Audio Asgard 3. This amp is really becoming my favorite with the class A design. I bought it with the dac multibit card, but prefer the stand alone Multibit modi dac running through it.  I've read that Schiit can't fit all of the circuitry of the multibit design on the small card.  The Modi has it all, though.

The Nads are on the warm side, the Asgard is said to be pretty neutral, with good detail and clarity. In the current very competitive amp market, the manufacturers have been putting out better and better entry level headphone amps.

I’ve had the Schiit Magni 3, and the Vali 2. The Vali 2 with modi multibit was delicious(sold it when I upgraded to the Asgard). Gorgeous sound for the money. But I never heard this finer detail with this set up that I described above. I have great respect for the Vali 2, but the Asgard 3 is a superior amp, definitely getting into higher end stuff.

Schiit Audio is really making some great sounding gear. For a one box solution, the Asgard or Jotunheim can each be ordered with their dac multibit card for a price of $399 or $599 price points. But for the best sound I’d recommend the Asgard with no dac card($200) and the Modi multibit($250), both in black. Sit the modi on top of the Asgard in the back corner, and connect with some decent RCA interconnects, I had a Audioquest Sydney sitting idle, and there is good synergy. The results are amazing with good files. And any of these options would be well within the budget

I’ve got the Nad cans, as well as 2 pairs of Bose, the better sounding one being the QC15($350 new). My favorite cans are the Grado SR125e, and for outside yard work I use the Koss Portapros. The Asgard sounds good with all of them. It does reveal, though, that the weaker Bose was not worth buying.

So the Ananda's were delivered yesterday. I have spent only a few hours with them, but so far I'm very impressed. They are much more resolving and revealing than the HD6XX. The soundstage is not only wider, but the depth and height is quite fabulous. It's the first time I've heard sound coming from above my head, which was quite an experience, especially for a newbie. Lots of air and much better instrument separation compared to the HD6XX. The bass is pretty good -- goes deep and more punchy than HD6xx for sure, but to be honest I was hoping for more. On some songs I felt that the overall sound character was a bit thin. I found myself wishing for a more lush sound. Hmm... maybe time to start exploring some tube amps?

But overall, this is a seriously good pair of cans. I'm really digging the holographic sound and the wide soundstage. At one point I thought the sound was coming from my main speakers, only to realize it was the Ananda's. Nice!

But here's the funny thing. After listening to the Ananda's for about an hour or so, I switched to the Sennheisers. Sure they don't have the same level of resolution, soundstage, and bass, but to my surprise they are not any less enjoyable. I don't know how to explain. I thought after the fireworks presented by the Ananda's, I would suddenly find the HD6XX boring and start packing for return. But that didn't happen. That midrange magic shines through despite everything else. I think the best analogy I can come up with is like wearing a new and stylish shirt when going out. But when you are back home, you put on your worn out, comfortable old shirt and kick back. Anandas are like the new shirt -- the colors are sharp, the fit and finish is perfect, and it has that wow factor. The HD6XX on the other hand have the intimacy and comfort that you long for when you want to just kick back and relax with a cup of your favorite coffee.

Yep, you guessed it right. I'm keeping both. The HD6XX gives you so much at such a low price that I find so endearing. I will listen to the Anandas when I want to do some critical listening or have some fun, but the HD6XXs will be my choice while working in front of my computer or when I just want to relax.

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@arafiq I just received the valli2. I have listened to it for it for an hour and it sounds so much better! I have no idea what the tube is as there’s no marking on it and its box.
I thought it would make music sounds much louder than I am used to, but no. It just sounds bigger, fuller with tons of more details/depth. I had to put it in high-gain mode and it is hooked up headphone out 3.5mm jack to RCAs to the schiit.
I had a chance to try it with both the 7506 and the HD598 - The improvements were very apparent on the 7506, but I am going to need more time to hear what the HD598 could not do before... this is my work setup... so I can’t wait monday!
No i am going to hunt for a replacement tube (they do not last foerever) , and most importantly a better 3.5mm to RCA Y-cable as the one I got is not connecting super well to my cell phone... suggestions welcome!
Nice to hear that the Anandas are a gem, if any cans achieve holographic sound, they’re keepers for sure!

And yes, the Vali 2 is something else!  Here’s a brand that I’ve purchased and been happy with, ixcc, good price and quality connectors.
Hope it’s okay to provide a link.
@arafiq — how many hours do you have on the Anandas?  Just wondering if they’re broken in yet.  Same thing @213runnin re: the Vali 2?
Soix, I guess you didn't read the thread?  My post from April 23 mentions that I sold the Vali 2 when I upgraded to the Asgard 3.  I put 50 hours on the Vali 2 when I first received it to burn it in.  I found it very much the better option over the Magni 3, but I've never heard the Magni 3+.
Quicksilver Headphone Amp..... it is built just like their amps.  Unbelievable sound for the money.  Best $1k I think I've spent on anything.  
I've put about maybe 20 hours on the Anandas so far. I know it's too early to form an opinion but so far they're quite good. The two things that I wish could be improved upon are better, deeper bass and maybe slightly smoother treble. I'm finding the treble a little too hot for my taste. Let's see if these aspects improve after burn in. Otherwise, these are really, really good and definitely a huge improvement over HD6xx.

@213runnin -- I might be completely wrong but from what I've read on other forums, the Vali 2 is not recommended for planars in general. I'm looking into the Jotunheim with the multi-bit DAC module installed.

@oddiofyl Thanks for suggesting the Quicksilver. Given that I'm particularly partial to the tube sound, I'm seriously intrigued. I know it's a little over my budget, but on the plus side this is something that I can buy once and never have to worry about upgrading for quite some time. I've only heard great things about the company. This amp can form a  stable foundation as I try out other headphones. Can you provide more details on how they compare to other headphone amps that you own or have owned in the past?
I wasn't suggesting the Vali 2 for the Ananda phones.  I was suggesting the Asgard, but the Jotunheim should be even better.
 @arafiq — you initially stated you have a preference for tubes, so why not look at the Lyr instead of the Jotunheim?
The HDXX is a very high impedance headphone- like nearly 600 ohms. It needs a slug of power to come truly alive. Paired with a powerful headphone amp, it outpunches its weight.

For me, the Woo WA22 is ideal with the HDXX, when running in balanced mode with a balanced source and balanced cables. The WA5 is also stellar but significantly more expensive.

You can land a used first gen WA22 for about $1200. Pricier than your budget but you won’t ever regret it.
@soix TBH, I wasn't even aware of the Lyr up until now. Will definitely look into it. Right now, I'm seriously considering either the Quicksilver headphone amp or the Feliks Audio Espressivo Mark II. But will definitely check out the Lyr's reviews as well.

@davehg I would love to get my hands on a Woo Audio amp but they're just too rich for my blood. I haven't seen a used WA22 anywhere. Let me know if you know someone who might be selling it.
Sorry for the delay.  I just picked up the RME AD1-2 DAC and in the short time I've had it , I haven't used it's headphone jacks.  I have listened to the Quicksilver with the RME as the source and it is an incredible combo.  This DAC has a firm grip on the bass and the QS amp's bass is quite improved over my last DAC.   

 So as I write this ,  I had to plug into the RME headphone amp.  Its OK,   I dont think it's as good the Rupert Neve RNHP.  It does not compare to the Quicksilver.  Not even close  

The Quicksilver is the best sounding amp I've ever plugged into.  I think in terms of sound quality it is better than the SPL amps that are twice the money. It has zero features and one input so that can be a deal breaker for some.    I'm using Klipsch HP3 and it is such a great sounding combo.  Can easily drive 20 or 600 Ohm just as claimed.  I have used a number of different phones and this amp has balls !!!
As a DAC the RME is phenomenal.   It sounds great,  I would have to say it's the best sounding DAC ,actually best sounding source I've owned and I have a number since the early days of DACs.    It's not a bad headphone section,  it is good but I have been spoiled by the Quicksilver .  If you have a good source, ie DAC your money is well spent on the Quicksilver.   For a one box solution the RME is great but when I say the Quicksilver is special it's because it is.  It is worth every penny.  I like separates and the Quicksilver's sole purpose is to be an amp.   
I'm using something called the Blockhead by HEADROOM.  They also have many other brands both new and used.   I would call/send an E-mail and evaluate his response.
@oddiofyl Thanks for your response. As a matter of fact, based on your experience and a few others, I ended up buying the Quicksilver HP amp a few months ago. I will say it's one of the best audio purchases I've made in a long time. I'm just surprised that there is so little information out there on this amp, and virtually zero pro reviews or youtube videos. Go figure!

I kind of went on a shopping spree and ended up buying a Sennheiser HD6XX, Hifiman Arya, Focal Clear and the Quicksilver amp all within a space of a few weeks. Right now, I'm using the Bluesound Node 2i as a streamer and DAC. I know that's probably the weak link in the chain but I need to slow down and stop sabotaging my retirement plans. Hopefully I will upgrade to a better DAC in a few months. I will keep the RME in mind when I get there. Good to know that you found good synergy with the QS amp.
Today, I was comparing my Sen. 650's in their balanced vs unbalanced configuration.   I can't say if the difference was with the cable connected to the amp, but the balanced connection was way better.  (stock single ended cable vs Cardas balanced, w/balanced amp)  Just sayin
@arafiq You might try Massdrop. They have a deal on the Violectric V280 which is a wonderful and warm sounding amp with power galore. It’s what I’d buy if a WA22 could not be cheaply had. 
@arafiq I got into headphones 6 months ago with the Meze Empy and Benchmark AHB2. That is $6K right there in the deep end. I got lucky since it was a homerun.

Last week I got a $500 Topping A90 headphone amp ($424 Black Friday). I also got a Matrx Mini-i 3 Pro DAC which arrives on Wednesday. I am burning in the A90 but when I have listened to it sounded very much like my HPA4. The HPA4 is considered by some as one of the best.

The Topping A90 is silent, dynamic, and overall great. It kills my prior Bryston BHA-1 which had some noise and game me fatigue. That unit is $2K new.

Take a look at this review from Hungary. I think this guy is right on the money for headphones. I actually bought the Topping based on his comparison to the HPA4.

I know you like the warmer sounding DAC.  These 2 headphone amps are neutral and will not add to the sound of you source, which maybe a good thing.

The Meze Empy with an upgraded XLR cable is amazing for long listening session with 0 fatigue. I get fatigue very easily. However, that is expensive. You may want to look at the Meze 99 as a gateway drug.

@yyzsantabarbara Thanks. I found that since I have a nice two channel system in my study I'm rarely if ever listening to headphones. I think you made the right move with the Empy since it has a laid back approach to sound which, at least in my opinion, is the way to go for longer listening sessions.  
The Empy in stock form is laid back and not ideal for me. Adding the WyWire Platinum XLR cable was what made the sound much more detailed and really perfect for my headphone needs. Since I have a toddler that goes to sleep relatively early the headphones come out each night.

An interesting thing that happened recently is that my floor stander connected to an all Benchmark stack is sounding great at very low volume. My COAX drivers on the speakers were replaced and breaking in now. I am not sure if I would have bought the  Empy right away given my new found discovery of the low volume sound of the speakers. At least it would have dropped in priority since 2 channel is my main squeeze.