Been listening since early this morning at a friends house (around 9 hours of listening at time of posting), another unexpected contender is a HPA-01M. There’s also a broadway here but I think that’s too far past portable to count in a comparison (even though you can use it as portable). So I guess it’s a 6 way shootout then. neat.
So, the c9 is good from initial impressions, it’s pretty well tuned overall and it depends on the mode you choose. Personally for what I like, I think the solid state class a and the tube a ended up impressing me the most when it came to texture, liquidity, and spatial recreation, where the solid state ab tended to be clean and punchy, but seemed to lack some intangibles compared to the a mode, and tube ab felt similar honestly of begging the question of why would I use this when tube a mode exists as it felt just almost blunt and lacking in spatial recreation mode imo.
I think the main appeal is going to be the tube class a mode, as that is a warmer sweeter signature of things with great timbre, tonal density, and texture without sacrificing much detail or control, but is easily on the richer and relaxed side of things, but I guess that’s what people want when they use a portable tube amp lol. I can def see the appeal on this unit, but so far, when comparing in class a tube mode to the phantasy ii, I don’t know if it was on the same level tbh, while the cayin was more fun tuned, it just didn’t sound as convincing and commanding on most headphones in comparison to the phatlab, it still sounded good, but imo not to the level of the phatlab. I do think that the c9 class a tube mode did almost meet the performance of the wa8 depending on the pairing, as it at times offered a more enjoyable tonal balance and also had more grip and authority over some cans that were harder to drive (for inefficient planar the woo does not preform well imo, but the woo takes off with a headphone it can power well). The woo did have a blacker background along with playing a bit better with some of the iems I had tried as well. Woo also had better detail retrieval, dynamics, and also better control given they were a headphone it could drive properly. They do go for a somewhat similar tuning and presentation but the woo feels more reserved and refined where the cayin gives you more fun, so perhaps a wash there as it will really come down to synergy but generally I think with the more efficient headphones the woo takes the cake.
There is hiss with sensitive iems on the c9 so that’s a bit of a bummer, and also the tube modes can get overwhelming with some iems so it’s a good thing class a solid state mode exists
When it comes to comparing a/b solid state mode to the bx2+, the bx2+ to me feels higher preforming when it comes to dynamics, impact, and spatial recreation, but the cayin might have a very very slight edge in timbre but not enough to make me consider using it instead tbh. Switching to class a solid state gets a bit more compelling, where I think the cayin might take the cake when it comes to tonal density, and texture and microdynamics, but the bx2+ still wins in macrodynamics and slightly spatial recreation since it offers more depth still than the c9 in this mode, but they much more closely preform on at least equal footing when comparing solid state a mode to the bx2+ (the cayin is more colored in this mode though so that’s something to note, it’s more relaxed and soft compared to the neutral forward bx2+). Also quick comparison to the amp inside the N8, the C9 is much much better executed
Edit: after more listening, the c9 might be an edge above the bx2+ now, I am hearing more detail now, and better bass texture and rumble (along with the better timbre and tonal balance), which makes it more compelling when using ss class a, so now it does feel like the c9 is a bit of a step ahead of the bx2 a bit
So far, I do really like the c9, but it’s kinda a bit pricey for what it is (1-1.5k would be more fair), as sure you are getting more options, but some of those options come at the cost of sound quality (feels like a portable pro ican almost). If you wanted something more colored and forgiving but fairly capable and enjoyed the idea of being to switch around, as you are getting 2 amps in one, but the other 2 options don’t feel compelling enough to add much value imo, and I think that it will really depend on how much you value having different amp modes, and for tube I would rather have a phantasy ii (or wa8 if you don’t have planar or plan for iems), but having them all in one device can be compelling so it is what it is
I already have experience with the bakoon which is a more neutral sweet sounding amp with a really enjoyable character, that does well with headphones but not iems. Current drive is also an option with this amp which works with some headphones and not others, the current drive out is very linear, fast, tight and controlled, and the voltage drive out is a bit more rounded warmer and forgiving (but also looser and less technical). Current drive works extremely well with planar and higher impedance, lower impedance dynamics were hit or miss for sure. Keeping it brief with this one, as a judge for performance can be something you can estimate below
I will say though, in the end, honestly the real winner to me has been the 424. I wasn’t expecting it to be this good at all. It has driven anything I reasonably threw at it extremely well. Super surprised how good the diana v2 end up on there with it’s lower power design for example. Only gripes would be impact could hit a bit harder and perhaps a bit more warmth could be nice, but like, it’s stage is very expansive and accurate (very pinpoint but realistic), the macrodynamics and microdynamics are on point, it’s resolution is pretty nuts for a portable, timbre is very accurate, and the texture is really really good. It has so far improved both iems and most headphones reliably with ease as long as you don’t mind a bit more neutral signature from the p6p. Really kinda outperforms the bx2 and c9 in technical performance while still being pretty enjoyable imo (although the cayin’s forgivingness can boost it’s enjoyment factor as well imo). The only reason my friend is selling this amp is because he doesn’t use it often since it’s not practical (low battery life, hassle to recharge, large), but man is the sound totally worth the hassle.
Some random thoughts on the diablo so far. Actually like this one a decent bit, it doesn’t compete at all with the stuff mentioned above, but as an all in one, it’s a solid offering and a step up over a micro bl, but with less features and a different signature that the micro bl enthusiasts may not be pleased with. The signature is more in line with something like the xdsd, where it’s more neutral slightly warmer and fuller sounding but a bit more forward than the xdsd, and honestly this isn’t a bad thing for most headphones. It’s a step up in control, resolution, dynamics, and refinement, although it’s staging feels somewhat mediocre and less expansive than the black label (it’s more accurate in placement but the bl feels more spacious). It really feels more headphone focused rather than the equally headphone equally iem focused micro bl. Using it as a line out, it’s a bit better in the dac section than the micro bl and also carries along that more neural but a bit of warmer fun signature the diablo has, but it doesn’t feel like a big improvement over the bl. Specifically regarding the bass, the micro bl is much more rounded, a bit looser, and more boosted, where the diablo is fairly clean, tight, and punchy. Man I wish this thing had an xbass boost lol (and a line in). Also looks/fit and finish, give me back the old micro bl design imo
To sum up things at this point, might as well do something I hate doing but needs to be done to get some content outside of these unorganized rambles. These quick at a glance comparisons assumes using cans/iems with proper synergy and will greatly depend on the headphone, and when deciding the spot for the c9, I averaged my experiences between class a tube and ss for simplicity (but that’s also a flawed approach and I really should be doing all modes but I’m lazy). The bakoon has also had it’s current and voltage drive outputs averaged cause laziness but mainly current drive. The wa8 was also only judged with 3 tube mode. Sources for the amps were a p6 pro and lpgt ti mainly and then a range of higher end desktop dacs briefly. And higher does not always equal better, decide that for yourself after looking at the metric. And just my experiences and opinions, don’t take this as fact of course
Overall performance with a wide range of headphones: 424 > phantasy ii > wa8 = hpa01m = c9 > bx2+
Overall performance with a wide range of IEMs: 424 > c9 = wa8 > bx2+ = phantasy ii = hpa-01m
Overall usability and feature set (things like size and form factor, connectivity, battery life, charging/maintenance, etc): c9 > bx2+ > hpa-01m = 424 = phantasy ii > wa8
Some sonic stupid simple comparisons that you should take with a grain of salt:
Generalized timbre (most accurate to least): wa8 >= phantasy ii > 424 = c9 = hpa-01m > bx2+
Generalized impact and slam (most to least): bx2+ > c9 = 424 = hpa-01m >= phantasy ii > wa8
Generalized resolving power (most to least): 424 > phantasy ii > hpa-01m > wa8 >= c9 > bx2+
Generalized texture (most to least): 424 > phantasy ii >= wa8 = hpa-01m > c9 > bx2+
Generalized microdynamics (most to least): 424 > phantasy ii > wa8 = hpa-01m > c9 > bx2+
Generalized macrodynamics (most to least): 424 > hpa-01m > phantasy ii = bx2+ > c9 > wa8
Generalized background (blackest/most vacant): 424 > wa8 >= phantasy ii = bx2+ = c9 = hpa-01m
Generalized hiss with sensitive iems (most to least): c9 >= bx2+ = hpa-01m > phantasy ii > wa8 > 424
Generalized source dependence/transparency (most to least): 424 > hpa-01m> bx2+ = phantasy ii > c9 = wa8
Generalized stage width (most to least): phantasy ii >= 424 = wa8 = hpa-01m >= c9 = bx2+ (still iffy on this one)
Generalized stage depth (most to least): 424 > phantasy ii > hpa-01m > c9 = wa8 > bx2+
Generalized tonal density (most to least): c9 = wa8 > phantasy ii > hpa-01m >= 424 > bx2+
Generalized smoothness (most to least): wa8 > c9 > phantasy ii > hpa-01m > 424 > bx2+
Generalized extension (most to least): 424 > bx2+ = hpa-01m = phantasy ii > c9 > wa8
Generalized forwardness (most to least): bx2+ > 424 > hpa-01m = phantasy ii > c9 > wa8
Generalized speed and separation (fastest): 424 > hpa-01m > bx2+ > phantasy ii > c9 > wa8
Generalized forgivingness of music (most to least): c9 = wa8 > phantasy ii > hpa-01m > bx2+ > 424
Will update this if things change or I look over this and realize a mistake. But it’s really going to come down to synergy and the type of headphones you have so the above is useless lol
seems a lot of these so called “portable” amp’s seem to be aimed at HP use and not IEM’s which I find kinda ironic, how hard is it to have an IEM match option like iFi? wouldn’t this make those type of amps way more appealing 
