AIYIMAT1 PRO Tube Preamp Vacuum Receiver Home Audio Preamplifier with RCA/Bluetooth & Bass Treble for HiFi Stereo Amplifier&Powered Speakers,with AUX/12V Trigger Signal Output

Turn out a very good edition to my system. Works very well between my old CD player and vintage Marantz home theater box. I also have an old equalizer in the tract. The bass is way softer, the sound all over is warm and charming. The blue tooth connects with no problem. The two sets of output allow the subwoofer connection, but the bass is so good in my homemade speakers that, in most cases, there is no need in subwoofer anyway. Three tone controls work okay. It makes really nice sound for the money.

That expression reveals my age, as does the stack of junk in the photo, where the Aiyima Tube T7 has found a home. I did order the upgraded tubes as well, but they haven't arrived yet. This is my impression of the supplied tubes.Hookup was simple. I ran USB into a Topping DAC into the T7's inputs, then connected the output to the tape loop on the Marantz receiver (lower unit). It feeds a pair of Klipsch Heresies, and a 250 watt 15" sub. I also connected my Android phone to the Bluetooth.First, the Bluetooth performance is exceptional. It pairs quickly and the sound definitely benefits from both the DAC and the tubes' effects on the signal.Running an UltraHD stream from Amazon HD from my PC over USB, it's arguable whether the Marantz benefits from the additional tubes and circuitry or not. Marantz of the the 60s and 70s is considered to be some of the best sounding gear ever made.Still deciding on that, I switched over to the slightly newer (1980) JVC, which has a clean amp section and 25% more power than the Marantz, but is nothing really special. On this receiver, the Tube T7 added a bit of "friendly bounciness" to the sound, a slightly warm colored sound that seems to bring the sound alive. This is a good match.With the Marantz, you'd have to decide for yourself. The effect is good for the most part, but imparts some sibilence and smear to high-frequency details. I'm anxious to try the new tubes, and even more excited to try running this through a class D amp like the A07 or brand new A08.And if you're just looking to add Bluetooth to your setup, this unit should definitely be considered.Update May 30, 2021The DollaTek upgrade tubes came, and they're a definite improvement -- but they're noisy! (It doesn't matter once the music's going, it's just a slight hum and hiss). The effect of these tubes on the sound is much rounder, less harsh, adding a slight bit of sizzle and shine to the higher frequencies. The tubes that came with the amp were near silent at idle, but didn't sound the same. I'd say not as good in my setup, your mileage may vary. Worth trying both to see the difference.Update June 1, 2021One knock against the unit is the microphonics exhibited by all the control knobs, because they are aluminum and have a firm mechanical connection through their respective pots soldered to the main circuit board. I'm not saying that I did or didn't hear this in the music, but it is easy to hear wearing headphones and using the knobs.

Setup was ridiculously simple, PC and iPhone found the Bluetooth audio device in seconds. I have the RCA inputs connected to a Scott (Solid State :( ) FM Tuner. This unit feeds the Tuner inputs on an H. H. Scott 222C (7189 Power tubes, 12AX7 audio tubes). Sounds great, nice and warm like you would expect tubes to be. I shall probably buy another to allow my daughter to stream to her EICO ST-70 (7591 power tubes and the same 12AX7 Audio tubes).I'll roll into some other tubes (6K4,6J4,5654) to see what changes. Overall, I'm very impressed with this unit.

This unit feels well made, is very compact, and looks good.I got it hoping to send music from a laptop or desktop computer to the T2, thus to my old stereo. After a little effort (very little, really), it all works, with the old computer, new laptop, and phone. I am mainly using it to play music from my very old iMac to my even older Marantz amplifier. The sound is good -- I didn't expect the device to do much to improve what are mostly mp3 files, but it sounds a bit better than the tinny sound I anticipated, less sharp, more round (this might just be my imagination). The tone controls are appreciated. I do like the dedicated switch between RCA and Bluetooth, rather than an auto over-ride type of thing.The only issue I have had is, if the connection is idle for a period of time (no music playing from the old computer, goes to sleep) when I awaken it, the sound is choppy. This is probably the fault of the computer, not the preamplifier. I just have to disconnect-reconnect the bluetooth connection on the computer and it comes back.I'll add that this maker has excellent customer service. I emailed questions and received very prompt replies!

I rolled the tubes to the 5654’s and it was ok for a while. Then it started to emit a very high frequency squeal that bothered my wife like crazy. So today I just installed the OEM tubes to see if that fixes the issue. I’m hoping it does.