The Way of the Audiophile

As I mentioned in a previous post, my old Total Bithead headphone amp/DAC suddenly lost all sound in its right channel a few months ago. Rather than consider it a setback, I took this as an opportunity to make some long-planned upgrades to make my music sound even better. This resulted in me finally getting these:

And this:

And ordering one of these to put between them:

And later got a great deal in a group buy on these:

A bit of terminology: every digital audio system has four components: the music as bits stored on a hard disk, CD or flash; a DAC (digital-to-analog converter) to translate the bits of sound output into an electrical signal resembling an actual sound wave; an amplifier to bring the signal up to a suitable listening level; and an output to turn the signal into sound waves. Computers and phones all have built-in DACs and headphone amps so you can plug headphones directly into them and listen away. But audio enthusiasts with more demanding ears prefer to use higher-quality external devices instead.

So anyway, my headphones (Sennheiser HD650s) and DAC (an HRT MusicStreamer II+) both came from Amazon within a week. My amp, a do-it-yourself Bottlehead Crack, is from a small company and took almost a month to ship, so I had plenty of time to break the headphones in without it. When it did come, it looked like this:

I was responsible for installing all the parts, soldering and wiring everything correctly, and assembling, staining, and finishing the case, after which it looked like this (the amount of time and effort involved is greatly understated):

So, over a month later, I was finally able to connect all the parts of my system and turn it on. The vacuum tubes in the amp dimly glowed and I knew it was ready to listen.

This amp is specifically designed for high-impedance headphones like the 650s, so I can't easily compare them directly with my previous headphones, Sennheiser's HD555s. I also don't have all the hardware to separately test every component of my system, so I will be reviewing partially the HD650s and partially everything at once.

The HD650s are my first real "audiophile"-grade headphones, a few steps up from my old entry-level cans. They lack some of the convenience features of the HD555s like a single-sided cable and are high-impedance, meaning they sound somewhat wimpy without a proper amp, but they are definitely superior in clarity. Everything sounds just a bit more realistic and clear, especially the treble and transients in my music. It was shocking to hear the headphones that changed my life in 2009 sounding noticeably worse than something else. They appear to lack the "Eargonomic Acoustic Refinement" reflector of the HD5xx line, so the imaging is actually a bit worse, but the superior clarity more than makes up for this.

I didn't test the difference the amp and DAC made separately, but together they definitely get the most out of the headphones. On their own, the HD650s seem a bit quieter on both the high and low end of the frequency range on top of how hard they are to drive in the first place. With the DAC and amp powering them, the high and low ends both sound "just right". The bass is satisfyingly present and powerful without sounding excessive or "boomy" in the least; it sounds balanced over the entire range of my hearing. The treble is similarly sparkling and vibrant, but again not overpowering. Without some really high-end gear I can't comment on how neutral the setup really is, but it definitely makes my music come alive like never before, without overly revealing the problems of my lower bit-rate recordings. The amp seems to drive them effortlessly; I only dare to explore the bottom third of its volume dial's range and I could very easily test which could go louder: the headphones or my ears.

On a design level, the HD650s are probably the most best-fitting headphones I've ever worn. My ATH-AD700s have a softer fit, but I constantly worry about them slipping down or off my head when I move. The 650s are comfortable enough that I can easily forget I'm wearing them, but at the same time I never worry about them shifting at all. They also have a split-pad design on the band to avoid putting pressure on the apparently-sensitive center of the head; I didn't notice this until I put on my old HD555s and immediately felt the contrast. The build quality is excellent overall, with the extendable sections of the band made of metal and the rest made of solid-feeling plastic. They have already survived being dropped once, but I hope not to test this again.

Anyway, as mentioned above, I also found a too-good-to-pass-up deal on some Beyerdynamic DT990 headphones a few weeks after finishing the amp. The DT990s come in three versions with three impedances: 32Ω, 250Ω, and 600Ω. Since my amp can easily drive the HD650s to uncomfortable levels at a quarter of the full volume, I went for the 600Ω version, which is hilariously quiet on my Walkman but still an easy match for the Crack.

Having had time to compare them, the DT990s really seem like a perfect counterpoint to the HD650s. The clarity and imaging are of fairly similar quality, but the frequency responses could not be more perceptually different. As the graph below shows, the DT990s have a big bass hump at around 100-200 Hz, and the highs are 5-15 dB louder. This difference in the highs cannot be overstated and is almost hard to get used to at first; after wearing the HD650s, the DT990s seem blindingly bright, even sibilant; the other way around, the HD650s seem dead and muddy. After some more listening, I'm more able to appreciate each headphone for what it is as well as the differences between the two.



Fit-wise, the DT990s are also very different from the HD650s. They have much, much less clamping pressure, which is kind of a relief, and the earpads are incredibly soft and comfortable. They do lack the split-band design of the HD650s, though, and actually get less comfortable (at least on the top of the head) after a few hours' use. It's not nearly as big an issue as with my Grado SR60is, though. They also have a handy single-sided cable design (which, sadly, is not detachable) and nice construction incorporating more metal. Despite this, they still manage to be amazingly light.

Overall, I think I actually prefer the DT990s. Yes, it's much less even, with a small boost in bass (which seems like it was overstated in peoples' opinions of the headphones) and massively boosted treble. This means that the drums (my favorite instrument in my music of choice), particularly the bass drums and cymbols, sound more emphasized with them, whereas the vocals and guitars feel stronger with the HD650s, which make metal sound a bit more substantive with their balanced approach to the mids. Both are great for metal in totally different ways. For lighter, particularly acoustic music, the DT990s are clear winners. If you ever feel like trying my setup and ruining sub-$250 headphones for yourself forever, let me know and I will be happy to oblige.