I didn't know for sure if it was synergy, but as other member replied speaking about that I thought he was speaking about it.
Regarding any amp (like the little dot), you can measure the FR w/o knowing the manufacturer's specs. After all how the FR remains after amplification is what is important.
Originally Posted by MrGreen
I don't think he is talking about synergy. He is looking for a way to determine which amp will power a headphone well; which i mentioned as "power output, potential difference and to a lesser extent output impedance": stats that we are not always given the liberty of (for example, if you take my now retired littledot for an example the output impedance is not given, and my now in use HR2 has very little specs available). Even then, I sincerely doubt that this is enough to determine how well a headphone will be driven (and it will give a better impression of how loud the headphone will go). You'd really need to wait for someone who really knows their stuff to chime in about it in more depth (probably someone who works in the industry).
That is where you are being subjective. You claim RSA amp is <on the warm side>. That means that the FR when measured is not flat (not talking strictly flat, just approx).
Regarding the two different amps you have tried being in two different leagues, what determines for you which one is in a better league than other, its price, name of the company who built it? As I mentioned before, if when measuring an amplifier (1, 2 or whatever number of them you want to measure), its FR remains flat or/and there is a very small difference between them (I have seen results like that, from different amplifiers, SS, hybrid,...) then that FR will most likely be ignored or not even grasped by you when listening to music.
|Synergy is indeed a subjective thing; for example I use the etymotic ER4P/S at the moment, which can seem a little cold to some and I am using an RSA amp - which means it is slightly on the warm side and rolled off in the treble (although not drastically). The treble is a little far-back for my taste but would be right up someone elses alley. For me synergy is about compensating for the perceived flaws of a headphone.
Unfortunately the only amp upgrades I have had the pleasure of spending considerable time with have been in totally different leagues and an ABX between the two would be pointless because the upgrade was so blatantly superior.
So I can't give advice on volume matching.
To put it simple for you as well, Plonter, what you will want for an amplifier to stay calm knowing your headphones are being correctly amplified (simplifying things) is that the input impedance of the amplifier is as highest as possible (from the choices you are looking for), and that the output impedance is as close to 0 as possible. Some amps like M^3 and Beta22 have an output impedance of <0.05. If your headphones have an impedance of 300 Ohm, you are going to want to use an amplifier with an impedance <300 Ohm. Very cheap to find an amplifier like that nowadays.
Regarding THD+N% you are going to want an amplifier with it value <0.5% (average percentage where above is usually heard by humans). That tells you the background noise of the amplifier.
Regarding what I marked, again, you can measure it at your home.
|@plonter, input impedance is more significant to your source than the headphones as it is the entry point to the amp circuitry (I.e. where you plug your amp in to your source, not your headphones). There isnt enough info given to tell you how well they are being driven in the specs provided. The most important specs that are usually provided are output impedance and power output, although something like potential difference would help even more, I suspect. But like I say, I have fairly limited knowledge on this.
If I am not wrong, the 600 Ohm rating was part of industry standards some years ago, now I think it doesn't need to be strictly followed.
|the ohmage of a headphone circuit is pretty arbitrary. It is more useful in studio applications (which if I recall correctly they either want a very low or quite high ohm rating - i suspect 600 ohm ish), however to us it at best tells us what type of power the headphone needs (whether it needs large amounts of current [low ohm] or not [high ohm] for the desired power).
Finally to the OP (and anyone interested), you might want to read the following:Audio SpecificationsUnity Gain and Impedance Matching: Strange Bedfellows Very important
This last link is very interesting as it also explains what you are really doing when you are using your headphones in a balanced configuration.
Hope this clears things up.