You know, I disappeared off these forums for a long while, and there was a story behind it. I didn't want to step on the toes of people who had been kind to me. I had countless notes full of so much writing I had prepped for all these reviews of all these different products I had planned, all these loans and all the rest.
The reality of it all...
One of my planned threads was a gigantic O2 vs V200 (and a few other expensive amps) comparison thread. The results of so many comparisons kind of shocked me.
I'm a logical personal, and I consider myself frugal and fairly technologically and financially savvy. I also have very good hearing and eye sight (Thank God). There was no way I was going to let placebo or hype get in the way of my impressions, nor would I let financial or product interests get in the way either, and that's why for my reviews I did outright blind tests, where other people would swap things around whilst I was blind folded and I'd A/B thousands of times, in-fact, I'd do blind tests on others too. Over the course of these reviews, because the results were so perplexing and oft controversial, I had to listen to hundreds of hours of music just to re--confirm my opinions.
The entire audiophile industry is a sworded one. Perhaps the most reckless and unjustifiably excessive of any technology based hobby out there.
Maybe one day I will care to write out some of my comparisons and reviews, but in the mean time I'll just say this.
If you want a strictly neutral amp, with no colour, that will power any of your high end headphones (bar electrostatic cans such as the Stax, as I have not tested with them and cannot confirm that), the cheap little O2 will be more than sufficient, and you will not get any better quality in a perfect flat, un-coloured amplification, moving to any other amp. The frequency response is straight flat, and the noise floor impossibly low, the power plenty. T1's, HD800's, LCD-2's, which I all tested on them, and compared with other amps, not an iota of difference in terms of power delivery or overall quality.
I will however add….
But there is a difference
Different amps, DAC's etc, DO sound different. Sometimes insignificantly different, sometimes noticeably so. For example, the V200 probably sounds around 10% different to the O2 if I had to put a percentage on it. However, that difference is NOT an objective difference in better sonic quality, only a subjective difference in sonic preference.
What I mean by that is, the O2 offers a perfect, pure flat response, with no issues in power delivery what-so-ever. The V200 only sounds different not because it's better quality in any way (though you may prefer the way it sounds), but because it colours the sound ever so slightly. It adds some added sub bass and peaks the low-mid range, and that's why it sounds so good with the T1's (and HD800's) etc. The T1's benefit a good degree from these minor colourisations, because these are areas of it's frequency range that it is lacking. It's the same reason many tube amps sound good with these headphones too. They essentially add colour to the sub bass and tame the higher frequencies, and some people like that, but you have to realise the amp is essentially changing the way your headphone was designed to sound, if it were powered ideally, and completely un-coloured.
Everything comes at a cost
However…..by adding extra colour to the sub bass and lower mid range, you automatically affect other areas of the sound signature. And no amp, irrespective of the price, will change that. Because it is a flat frequency and signal. It's not like an actual headphone that can change sonic delivery even in it's physical design, size and form (size of the drivers, ergonomics etc), the amp only has a set signal and frequency to work with. Changing one part of it WILL affect your perception of the others.
In this instance, with the V200 adding sub bass (etc), it very slightly clouds the highs and sound stage. Sound stage in this respect being a change in the sonic dynamic dictated by the bumped up bass, clouding the rest of the signature, which gives the false perception of a smaller sound stage. because of this, as much as the V200 makes certain elements of the T1's sound better, the O2 is actually still cleaner and more detailed sounding, and more importantly, un-coloured.
Did I prefer the sonic delivery of the T1's paired with the V200? Yes. But there was no way I was going to pay hundreds of pounds on an amp for just a smidgen of added colourisation in a few areas of the sonic range. The basic premise of an amp is to be absolutely colourless, and simply power your headphones whilst remaining so. And the O2 does exactly that, flawlessly in-fact.
The higher end amps I tested were not powering the headphones any better. Nor were they any cleaner sounding (as mentioned, the noise floor on the O2 is inaudibly low). All a few of them were doing is offering a slight colour to the sonic signature. Think of it almost like adding a forced, ultra clean EQ to your cans. If that's worth the extra to you because of the specific colourisation or changes offered, then more power to you. But if you just want a completely un-coloured, perfectly sufficient, flat amplification, the O2 amp is going to hang with the best of them, irrespective of what others on here tell you.
*Awaits a slew of posters telling him he's wrong*
I agree with most of what you say (own the O2 as well as the V200 so I do think I can at least claim to know how they compare to me). The O2 is dead on neutral and you won't find better price/quality anywhere. The sound of the V200 is to my ears better but I agree that it's for the reasons you quote. But the O2 has its limitations, more specifically when listening on higher impedance dynamic cans and if you listen to music either at high volume or that has a huge dynamic range. I fall in the latter category, listening to classical music. There the O2 simply can't keep up with the Vio (and I suppose with other high-powered ss amps). I suppose it has to do with the power requirements and the impedance variation across the frequency range: it starts distorting and dialling in extra gain doesn't seem to change a lot imho. If you want to hear what I mean, just listen to e.g. Stravinsky's 'Rite of spring'. It's not just me saying this, btw, take a look at newavguy's distortion's graphs. It's not a criticism, as I said it represents terrific value. Also, try driving a HE-6 (admittedly an extreme example) on the O2, there it's not frequency related impedance changes that come into play (ruler flat curve across the band) but raw power. I'm on the fence about it for my HE-500. That being said, the HE-6 is not the absolute power monster many people make it out to be, I'm currently listening to some Rameau with the HE-6 connected to my dark voice 337 dual mono OTL tube amp. At lower volumes it sounds absolutely great even though I can't imagine that amp delivering anything near the power most people would say is the minimum required.
In the end it's about sound preference and especially the music, an aspect one tends to overlook when hanging around these forums for too long.