Audiophilepure

In 2016, PSI Audio released the first active bass trap, named AVAA C20, which is fully analog. From then on, the company continued to develop the AVAA technology. In 2023, the first fully digital AVAA, the AVAA C214, was introduced. PSI is not the first or only manufacturer to produce an active bass trap, as Pass Labs had a large, floor-to-ceiling pipe-shaped active bass trap in the early eighties, and Bag End has produced the E-Trap since 2008. However, PSI did the same for the popularity of active bass traps as Apple did for portable music file players. Furthermore, PSI AVAA is the only solution that works automatically on all resonances, without any adjustments, within 15Hz and 160Hz, in such a small enclosure. While critics will object that digital processing is not 100% real-time, PSI indicates that this is not critical at such low frequencies, as the long wavelengths allow more than enough time for the required calculations.

https://www.theabsolutesound.com/articles/metaxas-sins-emperor-loudspeaker

I can’t in all honesty conclude this review without mentioning the problem I experienced with a couple of the Emperor’s electrostatic panels. While no reliability issues cropped up with the less complex Czars, two of the Emperor’s 15 electrostatic panels began arcing noisily soon after installation. The fix was simple enough. Kostas’ U.S. distributor, Jeff Garshon, came down with replacement panels, and all has been well since. I don’t know why this problem occurred, although it wasn’t as annoying as the failures I experienced with the CLSes, the entire panels of which (on both sides) repeatedly stopped making sound and had to be replaced due to hygroscopy, or the treble panels on Quad 57s, which blew up with the regularity of clockwork. Let’s face it: Electrostats can be touchy.

That said, do I recommend the Emperors (with the e110 tweak)? Yes, enthusiastically. They are very nearly ideal for absolute-sound and fidelity-to-source listeners (like me). For musicality-first listeners, who tend to like their rock ’n’ roll and like it LOUD, no, I don’t recommend the Emperors or any other full-range electrostat or dipole. These speakers are simply remarkable on classical music, large-scale or small, on jazz, and on acoustic rock, blues, folk, what-have-you. On heavy metal, electronica, rap, or hip-hop, there are better options. 

https://www.audiophilia.com/reviews/2026/5/23/staccato-audio-black-unique-bu-01-amplifier

Pressing the left knob turns the power on, and the volume levels are etched to its right in small white numbers from 10 to 100, in multiples of 10, with tiny lights above each number. Once on, the amp slowly and automatically cycles through the numbers up to 90, making clicking noises along the way, then snaps back to 10 (or whatever level you left it at when you last turned it off). A soft-start warm-up. The right knob controls small white numbers 1 to 6 representing the line inputs, with the current line in use having its tiny light lit up. Turning the left knob controls the volume, while turning the right knob controls the line in use. The tiny lights can be dimmed by using the right knob. But the unit comes with a well-made, simple-to-use heavy-metal remote control that fits in your hand (see the photo below). In general, I used the remote because of its simplicity and convenience, and it has a mute button.

https://www.stereophile.com/content/gramophone-dreams-109-stax-sr-009d-grado-signature-hp100-se-hifiman-susvara-unveiled

I tried the SR-009D first, because I wanted to see if I could tell the difference between my memory of the transistor SRM-700S I used for my SR-007S report and the SRM-500T I was using at home. I presumed I would notice some obvious trait that would distinguish the tubed drive unit from its transistor counterpart, but I can’t say I did: Apparently the JFETs on the input of both the 500T and 700S dominated the sound. In a blind test, I doubt I could tell which amp was which.On the other hand, the Stax SR-007S and SR-009D headphones sounded remarkably different. The 700S driver amplifier excelled at beat and rhythm-keeping, which emphasized or brought out the 007S’s finest performance traits: nuanced, uninhibited dynamics with palpable vocal and instrumental detail. At Audio46, the SRM-700S put more life and light into the SR-007S than into the 009D.

https://www.hifinews.com/content/unison-research-predm-v2-prepower-amplifiers

This is arguably what any hi-fi system should aspire to do – give an unfiltered view of the material – but I wouldn’t deny anyone seeking a softer sound, with more opulence in the bass. A counter to this is that the Pre/DM v2 bring their weight and drive to anything, making for a consistently thrilling, involving listen. Howard Shore’s ‘The Fighting Uruk-hai’, from the first film in the Lord Of The Rings trilogy [Rhino/Warner; 48kHz/24-bit], was rendered with astonishing power to the brass and percussion, giving this orchestral piece the scale and drama it demands. But even the smooth soul of Amy Winehouse’s ‘Love Is A Losing Game’ [Back To Black, Island; 96kHz/24-bit] benefitted from the amps’ dynamic flavour.

I listened to a lot of music through the Pre v2/DM v2 because I found them to be so much fun. Not fun to the point of being too eager or brash – there’s a well-balanced and finely detailed approach here that fits the none-too-shabby price tag and gorgeous styling. These are, however, distinctly powerful and energetic-sounding. Looking for a system to really get your foot tapping? Look here.