ฝรั่งนายนึงรีวิวไว้ครับ
http://www.diyaudio.com/forums/showthread.php?postid=1152546#post1152546The F1 is super clean and dynamic. If your source is lean, your music will be lean. If your source is rich, your music will be rich. It is the real truth machine, with nothing taken out and nothing added. Ruthlessly revealing.
The F2 adds some 2nd harmonic to this. On lean source material this sounds better than the F1. It is putting a little color in your music, and on dry material it is a pleasant addition. Some

that additional color, some do not. Your choice.
The F3 sounds has a very light touch of sweetness. Sounds more

a great tube amp than any solid state amp I have heard, except that it has the same basic tonal characteristics from highs to lows - something most tube amps dream about.
The F4 sounds

a cross between the F1 and the F3. Cleaner than the F2, a touch of sweetness, but the truth is still front and center. I have not heard this amp in my system (yet), so my thoughts about this may change. It is a very exciting product.