FX AUDIO Bluetooth Tube Preamp & Headphone Amp & Bluetooth Receiver+ESS9023 GE5654 HiFi Bluetooth 5.0 Vaccum Tube Preamp with RCA BT Input & RCA/3.5mm Headphone Output Bass Treble Control (Silver)

Just received and plugged into my Dynaco tube system. Very pleased so far, easy pairing, sounds great, I'll be running some tests for specs in a few days after tubes have burned in a bit. This review and attached pics are for the TUBE-03 Mk II, with built in bluetooth. I chose this because of the latest gen bluetooth chip as well as the ESS D/A chip. Both of these are used in much more costly bluetooth streamers, that don't use a tube buffer stage. As such it represents a great value, and the construction, knobs and jacks are high quality.

My preamp arrived essentially DOA. It powered up and that was the only good thing about it. Correctly wiring it between my RTR and Onkyo receiver resulted in no signal to the receiver. Pairing my telephone to the preamp again resulted in no output to the receiver. Plugging in headphones to the preamp resulted in muddied very weak audio. Also the on/off button didn't work - the preamp was always on - the only way to turn if off was to unplug the power source. Went thru the troubleshooting procedure with Amazon failed to correct the problems. Returned for refund and will try a different branded preamp.

The caveats... Lacking in turn on/power up delay/squelching, pops/thumps and with too high of gain with it and/or other components (audio and/or multimedia system dependent) could result in damage to other components and/or speakers. The gain/volume control, well, unsure if it'll last; notchy beast it is.(The unit itself, other than those aspects, is great.)The tubes are good, have had them for roughly 6mo. and are hanging in here; will have to see the longevity on them. The acoustical soundfield reproduction is nicely for such a small and moderately priced piece of equipment.[MblTchXprt]

SNR: 100dB (the higher the better)THD: 0.001% (the lower the better)look at the numbers above, this thing is very clean sounding. i have tried 5 different ones and this one wins.when you are shopping for any hifi audio device always look at the SNR signal (to) noise (decibel) ratio. and the THD total harmonic distortion % . THD means how much of the pure sound gets lost inside the unit. 1.0% or 1% is horrible. 0.1% is bad, 0.01% is ok. 0.001% is very good. if want really clean sound buy a good usb dac too like topping e30 with THD 0.0003%. also buy this ultra clean power supply for the e30 called iFi iPower Low Noise DC Power Supply with International Travel Adapters 5V . you will love how good all of this sounds

I don’t know if the tubes really interact like a tube amp, (they do light up) but it is a great addition to my stereo. A volume boost for speakers, a stand alone headphone amp and a cool Bluetooth amp that I use to play files from my IPhone through my speakers. Of its category, I think it has the most bang for the buck.

Bluetooth did not work at all. Tube placement was extremely flimsy. I recommend you do your study, save money and get a solid tube amp that truly has a Bluetooth capability.This product came across like a toy and not a tube amp. By the way I tried connecting it with three different iPhones in our house. Did not connect at all. Not sure if it’s a one off incidence. But returned this product after 2 hrs of continuous troubleshooting to connect via Bluetooth.

If your looking for tube sound this could work for you. I was looking for a tube amp and first decided to buy this as a preamp to see how my system sounded. Well I got a great deal since it works perfectly with my system and I got a tube sound at almost no cost. The Bluetooth works awesome... it has a lot of power for headphones, more than needed. I mainly been using it as preamp with Bluetooth for my speakers and couldn’t be happier. For the cost it’s more than OK, if your looking for a HiFi best of the best tube amp I think you should look somewhere else and also pay like 10 times more. If you’re just looking for nice fun tube sound with decent sound quality this is a great deal!!!!! Happy Costumer Here!!!! =)

There was NOTHING whatsoever to PROVE that the tubes that are included in the FX-Audio Tube 03MKII are a MATCHED PAIR. As a matter of fact, the tubes were NOT even packaged in boxes. They were LOOSE inside the box just floating around. The manufacturer wrote a message to me "saying" they were a matched pair. If you look at the separate advertisement for the "MATCHED" pair, they are SHOWN, IN BOXES with the TECHNICAL MATCHING SPECS PRINTED on the boxes. There was NOT even a separate sheet in the Tube 03MKII box showing the specs of the two tubes.