MR Mateo Head Bought his first Headphone Amp! PART 2
I broke this review into 2 parts because it was too frickin' long. Part 1 talks about the decision process and impressions of the hardware.
So, we bought an O2 and have been playing with it all day. The goal was to gain headroom for HDR recordings, a problem I experienced during my introduction to the HE-400s. I also figured it would be nice to have an amp that could power future headphones of, say, 150-600 ohms. While it would have been easier to just buy the O2+ODAC for $300 and call it good, I opted for the standalone amp, and would probably buy the DAC separately, since separate components have their advantages. I still think the price of entry is high, but that should wear off in a month or so.
For those that hate long posts: Problem Solved.
For those that crave detail, read on.
Performance: Full disclosure, I am NOT one of those persons that believes every change in equipment = change in sound. At least, not usually a big or perceptible change anyway. If you want a big change, buy some new cans. Amps serve a very specific purpose, and all I want is reliability, ample power, and easy and abundant connecting methods if possible. 80-90% of my listening needs are met with the weaker amp of my computer. It even sounds great to me, and I doubt there is much out there that would be an immediate "must have". Bottom line: recordings are heavily colored, compressed, and vary widely in presentation. Headphones with "sound signatures" and weird driver technologies are making choices about how recordings should sound as well. If your AMP, DAC, and Monster cables are ALSO screwing with your sound, what you have is total chaos and a pretty impossible problem to solve. Amps and DACs should pass a clean signal, that is about it. If they aren't, I consider that more a problem than a wonderful, redeeming quality. I run a laptop with Realtek 888 inside, and I have no idea how great it is (specs v. reality), but I know it seems clean, neutral, and performs great. It also rewards my ears when using higher quality recordings.
First and foremost, even at 2.5X gain (default), the O2 drives the HE-400s to painful volumes (for me), and is capable of making my quieter recordings much louder. I did hit the top of the volume knob while watching the Eagles "Hell Freezes Over", but switching to 6.5X again got me to a point I would not sustain for any real length of time. I heard some source noise at 2.5X and 6.5X while watching a DVD (just some slight background hiss), which wasn't typically noticeable. That said, I am not sure I can say, unequivecally, that I wouldn't seek even more power for headphones any less efficient (or similar) than the HE-400s. Even using a cell phone as source, however, volume was noticeably increased.
That said, I've got to admit that this little O2 made me wonder how I made it this long without an Amp. I have been using the HE-400s exclusively for awhile, and my ears have "adjusted" to them quite a bit. I may need to consider re-writing my subjective impression of sound quality. I have listened to most all the same tracks I demoed in my A/B comparison to the HD595s, and believe the overall presentation of the HE400s has shifted.
With all my EQ tweaks removed, I find that the HE's are much punchier and more energetic with the O2 than without it. The low bass response and midbass response seems stronger, and the treble energy, still there, is perhaps better controlled. The initial "lean" presentation which struck me when I started listening to these may not be replicated had I started with an amp versus starting with the computer itself. Any bass heavy track I've thrown at it so far can almost punish me with well-resolved bass energy. Pretty cool.
I don't find the Amp itself to offer a "cold", "warm", or "neutral" signature, as my sound overall is still giving me a great soundstage, lots of depth, and a wonderful sense that these planar cans are beautifully transparent whether given a difficult and complex song or a simple one. Vocals are still beautifully rendered. Their are no weird pops or noises whether plugging in, or switching to battery, nor is there a noticeable shift in perceived volume (power). What mostly happens is I resist the urge to crank it!
The HE 400s are definitely a more fatiguing can, but they are a better can amped than not amped, especially if you are using a lower voltage source (like me). I suspect that some improvement might be found in bypassing the laptop altogether, and using an ODAC would offer a good DAC with, more importantly, a 2Vrms output which could no doubt further reduce the opportunity for noise to enter into HDR recordings. It may also unlock a smidge of volume I may currently be missing (or introduce clipping). But even with some Chopin on, the amp is very "black".
I cannot close this review with the claim that the O2 has all the power you would ever want, nor would I claim that my headphones are absolutely better. But the amp is certainly doing its job, and I am very pleased.
But seeing that you greatly benefited from using the amp for uncompressed music and also considering that most of my collection is uncompressed, maybe I should buy an amp.
