Andy I am really glad you brought up the current capacity of the amplifier. When I was selling audio gear every customer was under the impression that more power a receiver or amplifier had the better it was. It was a real challenge to get them to understand that current is what drives the speakers or drivers in the headphones. I miss the days when audio gear manufacturers made the current specs available in their spec sheets. Since you brought it up is there any chance Cayin will start providing the current specifications for your portable audio products?
I tried the A35 with several headphones as I don't use iem's and found the power is fine for most headphones 35 ohms or less. Once you switch to 60 ohm and above headphones I found the power of the N3 was necessary.
I am truly torn as I really like the N3 and I would definitely buy one if the Sony A35/A45 were not also available and a better fit for my needs. I like the DAP's Cayin is producing and quite frankly I think Cayin is now producing the kind of DAP's I have been waiting years for Fiio to produce. I will continue to follow your product releases.
I am also looking for a new portable amplifier and I did demo the C5 but I was not thrilled with it. I found the look and build quality lacking a little. Does Cayin have any plans to expand their portable Amp and DAC/Amp offerings?
I start off as an user (audiophile) and then moving up the ladder as a reviewer in audio magazine, and finally developed my own Home Entertainment project, the 911 crashed everything and my investor pulled back almost immediately after the hit. So I didn't have the honor to work with customers at front-line like you, I come from an informed customer perspective when I learn about the real story behind the product specification.
I keep telling my friends that driving power is not the key of a good system (or a good amplifier to be more specific), we should pay more attention to the "control" which is a relative neglected concept that play a significant role in the speaker (or headphon) - amplifier relationship, and in my observation, the two key factors that affect the control capability are the current capacity and the damping factor, the latter is basically related to the output impedance of the DAP headphone jack in portable headfi applications.
With a deep history in traditional hifi product, Cayin sure understand the important of ample current supply in our amplification circuit, that's why we stick with the more old-school two stages voltage amp + current buffer approach in the headphone amp. section of our DAP. Our rated power output probably is not particularly impressive but I am pretty sure our current capacity is on the high side of the spectrum although we didn't provide the related figure in the specification table.
Certainly not a problem to prefer A35/45 over our N3 because of your personal requirements. The market is large enough to accommodate several good products at the same time. Budgeted equipment is full of compromises, so in many case its not a matter of better or best of its kind but rather best fit for certain customers.
Unfortunately we don't have any plan to produce an upgrade or revised version of C5. The C5 is aged but still well-received as a competitive workhorse. The power supply is almost one of a kind with battery at 11.1V (3x3.7V), old-school audiophile will appreciate the advantage to power an amplifier with a high voltage power source directly.