When 1+1=5. Given the published power rating, I was certain that the very inefficient HifiMan Susvara planars would choke. Instead they took off in full flight between 12-13:00 on the clock. I had headroom to spare. And that off a vanilla 2V source, not specially goosed high-gain exception. Clearly not all specs mean the same. At the same time, the very efficient Final Sonorous X were dead quiet. Even they gave the attenuator room to stretch to ~9:00 before things got too loud. The taper on this particular Alps Blue seemed cunningly matched to amplification factor and output impedance. By acing the most inefficient and efficient cans in our collection, it suggested that behind lean paper power hid a butch 4x4 that'll get you there no matter where. It was down to reporting on what this actually sounded like. Tubes without output transformers. Goats without horns. What should one expect? This wasn't my usual mode of transport. Time to take the road less traveled.

Not much but some glow even with the Psvane if one looks close enough.

Safe sex? But first, a brief stroll down Preamp Avenue. To see how Euforia would behave as a minimalist pre with manual volume, I inserted its OTL valves between the COS Engineering D2 DAC/pre and our DC-coupled ultra-bandwidth LinnenberG Allego monos. I had zero baseline noise even though I did meet the occasional tube cough or mechanical ping of heated glass expanding. I also had good useful range over the pot. Alas, multiple times the music cut out for quite a few seconds before resuming on its own. This clearly wasn't an absent-minded source. Rather, it acted as though a protection mechanism had kicked in. Having spotted mention of a new preamp safety mode for 2018's revisions, I asked Lukasz what that circuit was supposed to do. Eliminate an occasional tiny leak of DC perhaps? In which case, mine wasn't working to perhaps explain why my DC-coupled amps went into brief self protection mode.

D2 in full-gain (zero attenuation = 0.00dB) mode to let Euforia be in control of gain.

"The preamp safety mode for 2018 prevents some—very few—transistor power amps being overly sensitive to trigger their own safety mechanisms and mute. That's what happened to you. Imagine my surprise when I checked the serial number of the unit we sent you. Apparently it didn't yet have this new safety mode installed to be a cross between a 2017 and 2018 model. All Euforias leaving the factory now have it." Since this still didn't answer what happened to pre-2018 units to trigger amps into self defense, I asked Lukasz to be more specific. "We have two large capacitors on the pre-out. In some rare cases, you can have a brief voltage in excess of ~1V which some amps don't accept. This triggers their own protection. It's in no warm harmful to the amps. It's just annoying when the music drops out. The redesigned 2018 circuit rectified this issue. It was a very rare occurrence to begin with. For about 300 amps sold, we only had one or two customers with this issue." Plus proxy me. With my first casual encounter suggestive of a nicely dosed injection of liquidity and billowy spaciousness, there was thus no need to abstain from further dalliances. Also, I could try our Pass Labs XA-30.8. That might play straight through in now discontinued 'unsafe' mode.

Bypass versus triodes. Running the COS Engineering D2 into the mono amps was my bypass scenario. It meant a relay-switched resistor matrix right behind the DAC for a very short signal path inside the same chassis. For triode action, this minimalist analog attenuator would open for max 2V output and the signal route through Euforia to hear by contrast what its tubes might add or subtract to/from the direct connection. The 1MHz DC-coupled amps at the end were a strategic choice. Where our Pass Labs amp is heavier and darker to contribute certain quasi 'tubular' qualities of its own, the LinnenberGs are pure transistors in what might be called the Swiss school of ultra-bandwidth direct-coupled high-speed amps. Think very high resolution. My thinking looked at the resultant context of neutrality as a quasi 'black'n'white' backdrop whereupon whatever colouring Euforia injected would stand out as dead obvious. And I certainly expected some changes. Why else bother with tubes and call an amp Euforia?

For raw resolution, direct mode very obviously topped the tubes. Without the four valves, I heard more textural contrast. With them, the gradated differences between transients soft and sharp reduced and focus softened. This downplayed the varieties of feel between sounds which became more homogenized aka similar. The same held true for image specificity and, relatedly, depth layering. Direct had superior focus. That made for stronger separation, more precise mapping and higher staging distinctiveness. The key action which the valves caused is best called echoic fill. That term quite perfectly describes the sensation of tones hanging in a more reverberant wetter acoustic. The upshot was more lingering fuzz between and around sounds. This acoustic batting was mixed into and thus also mixed up with the primary panorama. Envision a fine blurring quite like a thin mist which blends out sharp transitions and lowers colour saturation. To describe the effect, audiophiles often point at sepia vintage photos. It's unmistakable and somewhat romantic.

Another fitting visual would be foundation makeup. Not so thick as to obscure heavy blemishes, it does even out a complexion to make it more consistent and smooth and fill in bigger skin pores. Particularly for listening at lower SPL and despite the effect's relative mildness, I experienced direct mode as strictly superior. Without that comparator, one would simply play the tubes a bit louder to experience similar openness without ever suspecting that other hardware would show more at lower volumes. If asked whether in the above context the OTL bottles did anything better to earn their lunch, I'd say no. I noted the differences as described but given my listening bias and that specific hardware, wouldn't pursue them. Even if the less was quite little, I'd want to hear more not less. If instead I ran our rather drier nCore-500 monos into our Accuton-fitted Albedo Aptica speakers however—translation: class D into hard ceramic drivers—I'd definitely want the Euforia moisturizer. If I wanted that without any resolution loss, I'd have to reach for our tubed Nagra Jazz at six times the Pole's ticket. Ouch.

On a side note and to veer off Preamp Alley into pure headfi highway mode, the Pass never once muted itself. With the 2018 change and given admirably zero-noise operation, using Euforia as admittedly minimalist preamp is a fully considered part of the package, not an afterthought. Upon plugging in an earspeaker, the pre-outs don't auto mute. Whatever amps are connected must be powered down. And if you run something as inefficient as the HifiMan Susvara which want 13:00 on the dial or more, you definitely want to turn the amps off first since, as in our case, they might play plenty loud at 9:00. Past high noon, that could get really scary and not just your pink bits might wilt.