Sold: Andix Audio HPA-45 DHT tube amp (with internal WM8741 dac)
Listing ID: 61225 Views: 877
750.00 USD
Ships to
  1. United States of America

Andix Audio HPA-45 DHT tube amp/WM8741 dac - $750 shipped including paypal fees

Selling my Andix Audio HPA-45 tube amp-- this thing is really special, probably one of if the most compact directly-heated-triode SET tube amplifier out there. With a footprint of approximately half the size of an A4 sheet of paper, this tube amp also packs a built in wolfson WM8741 dac with USB/Spdif digital inputs, 1/8" aux and phono inputs (can be used with a turntable or cd player directly!), as well as both speaker and headphone outs, allowing this thing to serve as an extremely versatile all-in-one device. It features oversized highlight-core output transformers hand-wound by andix themselves (by a person who used to work for tango), and is a fixed-bias amp that can be adjusted with the built-in knobs and the biasing current meter.

Sound quality wise, this amp brings out the essence of 45 tubes's linear and transparent tonality. It has some tube bloom, but unlike some other cathode bias tube amps, doesn't have rounded transients and sounds nice and tight due to it being a fixed-bias amp. The sound is balanced and sweet and resolving, with great macro/microdynamics (to put it in relative terms, it's somewhere between the piety and the DNA starlett, leaning a lot closer to the starlett in my opinion). I loved this amplifier with the utopia for its ability to warm the utopia without making it too rounded/syrupy, but I feel it has the best synergy with higher-impedance stuff like the HD800 and hd650 and other mods (specifically loved it with the JAR800).

Regarding the condition of the amp itself, it's in good condition and in great working order. I tried to clean it, but there may be some dust in the very small crevices. This amp has been used lovingly for a couple years, but the tubes have lots of life and two sets will be included. Any st-type 45 tubes can be used, even unmatched pairs, since you can manually adjust the bias for each tube anyways. (Although important note: you CANNOT use globe type tubes it may damage the amplifier!!)

This will come with an included external powerstream 12V 6.6A laptop power supply, an AC power switch, a 1/8-to-XLR ZMF atmos S adapter, a grado 1/8-to-1/4 adapter, and a rca-to-1/8 aux adapter, as well as two sets of 45-st tubes and 5 sets of 6AU6A tubes.

Selling because I've decided to leave the hobby completely, and as much as I love this amplifier, I've already sold my headphones and associated audio equipment, so this is no longer needed for me. Of all my equipment, this is one of the most difficult for me to let go (which is why I'm selling it last), because of how unique, compact, and good it sounds. I will miss this amp.

Some more details:
  • Again, this is a fixed-bias amplifier that can be adjusted using the twist knobs with a screwdriver and paying attention to the bias current meter
    • The bias must be set to 24ma-- I recommend tuning the bias once the amp has been turned on/warmed up for some time, like an hour. After it's set, it usually doesn't need to be adjusted for months after, and then only slightly when needed (you can always monitor the bias in real time by checking the meter)
  • This uses 45 st-type tubes and 6AU6A tubes in single-ended configuration
    • This will come with two pairs of 45 tubes (one matched pair RCA, and matched one pair National Union), and five pairs of 6AU6A RCA tubes
  • NOTE: the andix doesn't have a power switch on the device itself-- use the included ac power switch (or just remove/insert the power plug to turn it off/on)
  • This devices uses an external power supply-- a high-quality powerstream 12V 6.6A laptop power supply and an ac power switch are both included (powerstream used to make the external power supplies for apple devices)
    • I would not recommend using a linear power supply, as one that is at least 12V 5A is needed and one of those is HUGE, hot, and bulky, and not worth it imo (believe me, I've tried with one that was over $1000 and it was not worth it because it overheated-- and this laptop supply sounded better imo)
  • While this amp does have speaker outs, it's only meant to power efficient desktop speakers, not a full speaker system
  • Headphone output impedance from what I could find is somewhere around 16ohms (so it's better suited for high-impedance headphones)
  • Note that USB input is limited to 44/48kHz, 16bit -- for higher input lossless, highly recommend something like an external digital streamer, like the pi2aes with spdif (which is what I used for a bit, before I switched to usb for convenience).
    • That said, the internal wolfson dac does have great synergy with the andix amp-- a slight warmer tonality and great sense of dynamics.
  • Features a gain switch for high/low gain at back.
    • For high-impedance headphones and general listening, I prefer the high impedance for the extra slam and engagement factor
  • Full disclosure: amp very occasionally makes a slight whine sound that’s more audible with lower impedance headphones (and not very noticeable with high impedance headphones like the HD800). It's rare and I can’t reproduce it with regularity-- usually it seems to happen when the amp has been on a long time (3-4 hours), though sometimes it never whines. Most of the time the amp is very quiet, but just thought I'd give full disclosure for transparency.

Asking for $750 including CONUS shipping (paypal fees included!).

Will be shipped fully insured with adult signature required. Everything will be packaged very carefully. Not looking for trades as I'm looking to get out of the hobby at this time.

Happy to answer any questions, and thanks for reading/checking this out!
Listed by: pure5152 (41)
Listed: 2024-01-22
Last edited: 2024-01-22
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