Pros: good detailed and revealing DAC; clear/revealing amp; lots of connections; heavy and nice looking build
Cons: you need to leave it on; cold dry amp without much warmth/bass; not good with all types of music; bad USB driver; slight line noise on preamp/DAC out
First a bit of background on my experiences with headphone amps. I have tried the Fiio E17, Objective 2, the 2.3W amp built into my laptop, my Yamaha receiver's headphone out and a cheap $40 Chinese tube amplifier. I got rid of the E17 and Objective 2 because after careful listening, they did nothing my 2.3W laptop amp couldn't do and so were a pointless waste of money. The tube amplifier though did impress me, it was super powerful, brought out deep bass that none of the other amps could do (although the Yamaha receiver got close), and added a nice warming effect which blended well with the HD800. I have also tried a number of DACs all of which had their own sound and I heard that the ES9018 sabre is the best DAC out there. I was investigating $1,000 well implemented ES9018 DACs when I decided to bite the bullet and buy what audiophiles said was the best ES9018 DAC/amp combination out there under $2,000.
Now let me go through the problems with this product one step at a time.
You need to leave it on -- The first thing I noticed was that right out the box it sounded slightly but annoyingly airy and tinny. I thought this thing had 4 watts. That should be more than enough to deliver deep thumping bass to my HD800. I was quite shocked at the subpar sound, until it started to slowly improve over the hours. I thought it was my imagination but then I read the manual which confirmed that this improves the longer you leave it on, even over days. I imagine that has something to do with the way heat affects the conductive ability of metal. The manual says that once you start it, you should give it a minimum of 30 minutes to warm up before listening, and suggests that it should be on for days to achieve its best sound. Any way, after it was on for hours, the bass/warmth were acceptable. Still not as good as the tube amplifier or Yamaha, but at this point it was simply a subjective matter of tastes vs. a clearly deficient product.
You might hate the amplifier -- Having said the above about subjective vs. objective bass tastes, even after it's fully hot and operating for three days, I can't help but to conclude that this could be a warmer sounding amp with more bass impact. This might not matter as much if you're driving, say, an Audeze (I didn't test that, by the way), but it does matter if you're driving something like an HD800 and you want an amp that really brings out the HD800's secret warmth and subwoofer capabilities without sacrificing the treble. This thing has like a $1,000 solid state amp built into it with all this fancy "no IC" components blah blah blah and a whole bunch of other rhetoric that you can find on their website. But who gives a crap if its frequency distribution is off? Burson, why don't you worry a little less about ICs and a little more making sure that you go the frequency response right? This supposed 4 watt amp can't even outperform a cheap $40 Chinese tube amp when it comes to delivering the warmth, exhilaration and bass necessary for some songs. For example, Al Jarreau's "Morning" is unlistenable on this. How did you suck the warmth out of Al Jarreau's voice?! The song sounds dry and irritating to the ear. I could list numerous other examples. I think it's amps like the Conductor that give the HD800 its reputation as a headphone that can't deliver top-tier bass/warmth. I often wound up connecting the Conductor to that cheap $40 tube amp to enjoy its ES9018 DAC with a proper amp. To its credit, the Conductor delivers sound transparently and clearly with no line noise (when using a headphone), and the tube amp is muddier -- but why can't we both micro-analyze the music and enjoy it too? Bottom line is that a $1,800 amp should handle every genre of music, and it should never be beaten by a $40 Chinese tube amp, ever, not with any song. I will never put my HD800 down to wear a $50 headphone and the same should hold for an equivalently priced amp. I don't know how much better a proper tube amplifier such as the Valhalla will sound, but I'll update this when I get such an amp. It's not only tube amps though. Even my Yamaha receiver sounds better at times, and that's solid state, and even my laptop's amp/Realtek 269 sometimes sounds better. Any way, since this is more of a niche amp designed to present some warped dry, cold, "reference" version of songs and not a song you would enjoy -- I feel I have to deduct 2 stars.
Edit: Eventually I got used to its "style" of presenting music and I guess diversity in musical flavoring isn't a bad thing so long as the buyer knows what they are getting, so I'm not going to deduct anything for this. This was clearly an amp designed to optimally present classical music: piano, violin, harp, horns -- not much bass and warmth in those instruments. Rather, those instruments have a lot of mid/high treble and the Conductor's revealing nature is very well suited for such sounds. And to be fair, it's called the "Conductor" not the "Rock star," so it's not like they're trying to mislead the buyer.
The ES9018's boost in detail won't be worth the price for all but the most nitpicky consumers -- After lots of careful listening, the ES9018 does have a slight detail boost over my other DACs with most songs. You can hear tiny background things, or details in foreground sounds, that weren't as noticeable on the other DACs. I say as noticeable because once I try to listen to them on the other DACs, I can often see that they were there, but those DACs didn't separate the detail push it forward as well. The problem with this is diminishing returns. Any modern DAC worth its salt will deliver enough detail to allow you to thoroughly and fully enjoy the song. Sure, back in 1991 when soundblaster had that awful sound card that couldn't handle anything more than I think 8 bit / 16khz, DACs were bad. But those days are gone. All of my phone DACs, my $87 Chinese PCM5102 DAC, and my laptop's Realtek 269 put out perhaps 90-99%% of the detail that this puts out depending on the song and your setup. Is it worth it to spend $500 to $1,000 to get an ES9018 that puts out a few extra irrelevant sounds? Let me compare it to an analogous decision you'll have to make: Was it worth it to get an HD800 to plug into my laptop, vs. plugging a $300 headphone into the laptop? Hell yes, absolutely, I recommend that purchase for everyone who wants good sound. Or if you don't like the HD800 get some other high end headphone. Those are a good buy. Consider it a 10 year investment costing you $12 a month or so. There is a huge and noticeable improvement when moving to an HD800. But don't overestimate the improvement in detail created by the ES9018.
The USB driver is defective -- Sometimes, when you finish a song and a new one starts, or a new youtube starts, all you'll hear is silence and occasional random bits of a sort of static popping sound. Well eventually I figured out that in these situations you need to restart the music player a few times and the USB will fix itself, but this is not a problem I have ever had with any other DAC in any way, ever, in decades of computer audio. Hey Burson, why don't you spend a little less time bashing ICs, whatever they are, and a little more time competently programming your USB driver? Even my cheap $87 Chinese PCM5102 xmos DAC doesn't have this problem and that was essentially built by a DIYer selling stuff on Ebay. I'm deducting 1/2 star for this.
Edit: The USB issues is now a much rarer occurrence, for whatever reason, so I won't deduct any points for this.
Line noise -- This has three ways to output sound: a DAC out RCA, preamp out RCA and of course the headphone out. The preamp out has a faint high pitched squeal that is tolerable but annoying, and the DAC out has even more line noise that in my opinion is intolerable. These were tested by plugging those sources into my Yamaha receiver's line in or the Chinese tube amplifier's line in. I know what you're going to say -- there's probably something wrong with my power strip or power line conditioning or whatever, and that indeed probably is the actual culprit here, but regardless some of my other sources on the same setup do not have the line noise and I expected more from a product this expensive. Ultimately, I wound up connecting it to the receiver by using the headphone out and converting that into an RCA L/R, which had the least line noise (although even that had a very slight high pitched squeal). However, since I don't hear any line noise when using it purely as a headphone amplifier, which is its purpose, I won't subtract any points for this.
On the positives -- I guess it's a good "reference" dac/amp. Good if you want to study the music. The build quality is also obviously excellent as you can see in the pictures. It also has a ton of inputs and outputs (but again the output might create line noise in your system). Overall, this would be a good addition to your mix of amps and DACs. That's how I'll use it -- it'll my hyper revealing technical DAC setup. But at the same time, depending on your tastes, there could be much more important audio products to spend on.