Blown away by YAQIN MC-13S - tube amplifier

A couple weeks ago, I decided to try the YAQIN MC-13S which I could order easily on Amazon. I figure that with the Amazon Prime membership, I could demo the amp for 30 days; and if I do not like it, I could return it easily.

.... My system comprised of the Benchmark DC1 (DAC) which goes into the Parasound Preamp which feeds the Mark Levinson no. 27.5. My speakers is a pair of KEF LS50's. The system sounds great in my room (which has the size of a normal master bed room). The total cost of Amp and preamp is about $5000 at the time I bought my system; and I think it is decent enough for my purpose which is just to enjoy music in the most natural way without too much listening fatigue. My system is connected using AQ cables .

.... Just for curiosity sake, I bought the YAQIN and just plugged it into my system . The YAQIN just basically replaces the preamp and the amp. Everything else stays the same.

When I turned on the YAQIN, I was blown away. The sound is so much bigger. The treble is sweet and has higher roll off then the Mark Levinson. The mid rang is lush and beautiful. The sound stage expandes to the point that I think I am listening to floor standing speakers. I cannot believe that my speakers could be able to produce such sound that is so beautiful.

Now having said that, I also found one flaw of the YAQIN which is the weak bass. The Mark Levinson gave me a strong and tight bass with a full body mid bass, the sound is not lean but leaning a little bit toward the warm side.The YAQIN gives me a weaker bass and some what bloated at the bottom end. I am not a bass head, but it would be nice to have a more refined low frequency production.

So far, I am very impressed with the tube amp. Even my wife notices the different, she even asked me what are the hot light bulbs doing to the sound ? She thinks that music sounds more natural now comparing to the old Mark Levinson. She is now spending more time with my CD than ever before which I found very nice.

I just want to share my experience regarding the YAQIN. If any one used the YAQIN or has any suggestion to improve the YAQIN any further, please let me know. I am actually thinking about selling my Mark Levinson and the Parasound Preamp and just keep the YAQIN, but I still hesitate because Mark Levinson makes such very good amp with good reliability. I am not sure about the YAQIN quality control though.

As all way, in this hobby, we share and discuss ideas. So please share, if you guys have any idea... I will appreciate that.