There is not much information on this amp around here, but a few members have one. I was feeling nostalgic and thought a group project to remember college would be fun. Luckily, @AMW1011 and @porkfriedpork were willing to oblige. It wasn’t exactly like college, since everyone participated and nobody got mad enough to go crying to the professor, but it was close enough. The setups of the individuals referenced are as follows: @porkfriedpork < HD800 < IHA-1 w/ PSVANE CV181-T & RCA 5U4GB < Gumby @AMW1011 < HD800 < IHA-1 w/ Sylvania 6SN7GTB & RCA 5U4GB < misc. DACs @MrTeaRex < HD650 < IHA-1 w/ Ken-Rad VT-231 & RCA 5U4GB < Holo Spring Additionally, we all have the optional step-up transformers and consider them a necessity with most headphones. Even with the input transformers, @porkfriedpork occasionally wanted the IHA-1 to have more volume on quiet tracks with high dynamic range, but admitted that he listens entirely too loud. @AMW1011 found the extra gain provided by the input transformers was more than enough to push the ZMF Blackwood and HE-1000 to critical listening volumes with quiet tracks. Two of us have tried the preamp functionality and would advise buyers spend the money elsewhere (more tubes). The preamp option was added as an afterthought and its tendency to hum sounds like it. One of the interesting aspects of the IHA-1 is that the tone and frequency response can react wildly to tube changes, including rectifiers. This means the following impressions are attempts to generalize the character of the amplifier as a whole. Overall, it is far from bright or harsh and leans more towards dry or neutral than wet or warm. The IHA-1 is not one of the numerous amps in this price bracket typically described as musical or tubey. Based on its price range of $1,600 to $2,150 (depending on options), the attributes were organized into three categories: exceeds expectations, meets expectations, and below expectations. I used an ECP T3 with all of the approved Beezar upgrades as a reference, since many members have owned or heard various versions. Starting with the good, the IHA-1 exceeds expectations in several areas: clarity, dynamics, imaging, and stage. The IHA-1 is clearer than the T3 and exhibits a blacker background. Macro dynamics and impact are noticeably improved when switching to a 5U4GB rectifier. The stock 5Y3GT was soft to the point of mushy in several instances. I’m typically terrible at assessing stage and imaging on headphones, as it only ranges from bad to worse. That said, even I was able to recognize an improvement over the T3 in depth, width, and positioning. @AMW1011 commented that it has the exploded staging you would expect from a good tube amp, but does not lose the natural layering and body. Depth is pretty good, but width is the strength. Since this is not a budget amp, expectations are above average and were met in the following areas: resolution, transparency, mids, and high frequencies. I felt that the T3 and IHA-1 were similarly resolving and transparent. @porkfriedpork noted that the IHA-1 was not as transparent or source dependent as his Cayin iHA-6 and he could not compare DACs as easily with the IHA-1. Neither the T3 or Cayin are as expensive as the IHA-1. However, we each felt that those amps are more resolving than their prices reflect, so the IHA-1 met expectations. Everyone agreed that the mids were balanced and the highs extended sufficiently. @AMW1011 depicted the treble extension as good, but not exceptional, and would expect more if compared to a TOTL tube amplifier. We had one area that was a point of contention so I’m placing it here, between the meets and below expectations. I felt that the low frequencies were lean and slightly rolled off. Both @porkfriedpork and @AMW1011 disagreed and characterized the bass as well-extended. @AMW1011 went as far as to describe the extension as nearly endless when tested with the HE-1000. This discrepancy could be partly attributed to the fact that I was using the HD650 versus their HD800s, or that I was using the T3 for comparison. However, he further explained that the bass is not super-layered, which may be in line with what I heard as lean. We (happily) agreed that it does not have the rounded sound gaining in popularity. Finally, the areas that were below expectations: transients, attenuator, headphone jacks, and microphonics. The T3 was audibly more responsive in busy passages and I don’t feel the T3 is any better in this regard than a similar solid-state amplifier. @AMW1011 offered that the IHA-1 was quicker than most amps he had heard, but not the fastest, or up to the level of a Ragnarok. @porkfriedpork expressed that the DACT stepped attenuator made volume matching and comparisons more difficult than necessary. I still can’t figure out what would possess a designer to put locking jacks on a consumer headphone amplifier. The IHA-1 is fairly small and the locks could cause the amp to take an unnecessary spill during any mishaps with the headphone cable. I also discovered that the amplifier was more sensitive to microphonic tubes than my other 6SN7-based amps. Neither @porkfriedpork or @AMW1011 have had issues with microphonics, so YMMV. In conclusion, we are all more than satisfied with the performance of the amplifier and plan to spend the foreseeable future with it in our possession. If the preamp option is avoided, we feel others will be happy as well. @AMW1011 gave it the highest praise by saying that he stopped caring about amps after spending time with his IHA-1. **UPDATE (26-SEP-17): I was recently informed that the preamp outputs are no long an option and are now standard on every unit. As a result, the base price was adjusted up to $1,699 from the original $1,599. P.S. I'd also like to plug @aornic and his review site (http://aornic.com/). Many of these discussions occurred after the three of us were tagged as “Chasing the Dragon” in his Discord server.