In the context of a private listening session at headphoneauditions.nl (great experience btw, well worth the trip to Amsterdam and the cost of the service), I had the chance of trying the SR1a and doing some direct comparisons with my current Abyss Phi TC setup (see signature), which I was able to replicate at the shop.
The amplifiers I was able to pair to the SR1a were the Chord Etude (100W/8Ohm) and the Thrax Enyo, a dual mono class A tube integrated with 50W/8Ohm output rating.
I would say the SR1a are an 'experience' of their own, and their trademark definition as Earfield Monitor is a really appropriate one.
Since the very first few seconds after wearing / listening to them you get this unique mix of headphone and near-field speaker feeling which I enjoyed very much, both in terms of comfort and fit and as a way to obtain a large and diffused headstage.
The most striking trait of the SR1a to me was their extreme micro-detail resolution capability, significantly exceeding any headphone I have ever heard, including the AB-1266 Phi TC. I would define this more as a 'technical feature' than a 'benefit', because (over)exposing microdetails is - to me - satisfying in the short term (the wow! effect) and as an analytical tool - like in a studio editing session, but not necessarily something that gets me closer to the reproduction of the live perception of the music.
I was impressed by the SR1a speed (especially with the Etude) and the sense of air between the notes and between the instruments.
In terms of timbre, I liked the midrange and treble most of all - while on the leaner side (better with the Thrax). The vocals, both male and female, were presented in a very realistic fashion and with no traces of sibilance and harshness which are sometimes a by-product of headphones with high detail retrieval and airiness. Abyss TC vocals sound, in direct comparison, a bit rougher and less 'real'.
As for the bass, the SR1a are not bass light in asbolute terms, and both the quality and quantity of their bass were above my expectations. However, I must admit that I missed a lot the sense of physical satisfaction - even euphoria at times - the Abyss are able to deliver through their deep, fat but fast and resolved lowest end.
By adjusting the earpieces I could manage to tune the balance between bass extension / impact and soundstage extension / imaging focus, but some tracks (organ, of course, but also some vocals with deep double-bass plucks) were simply not enjoyable to my ears with the SR1a after hearing them on the Phi TC.
Headstage, imaging, instrument separation were very good as well, but I preferred the Phi TC more cohesive and deeper staging. I had the feeling that the SR1a tend to present the music in an hyper-realistic, even mechanical fashion at times, which is somehow a different experience from what I get in a real concert venue, which the TC mimics closer IMO.
Among the two amps I tried, tonally I preferred the Enyo warmer / darker signature compared with the Etude, whereas the Etude won in terms of speed and bass impact. I was relatively surprised that the Enyo - rated 'only' 50W - was able to drive the SR1a well above my typical listening levels (80-85dB), with no feeling of being strained.
Overall, I really appreciated the SR1a and I am quite sure that with some more time with them (allowing better brain and mechanical adjustment) and perhaps with a further optimization of the amp pairing they could shine even brighter. That said, as I realize I am biased towards the Phi TC, I would not see the SR1a as a replacement to the Abyss, more likely as a complement to enjoy a different / unique way to experience listening to music through headphones (or Earfield Monitors
).