I've a pair of Kef Reference 105/2, not the Matrix, but very similar in speakers size (12" woofer), cabinet, and even less sensitivity.
When I bought an ECI-3 integrated, I must go 11:00 o higher the pot, to real sound. With a Sansui amp (2x100w. RMS into 8 ohms) they sound very well.
Now, I have an ECI-4, but not the 105/2 (I sold it and get a pair of 104/2, with 4 ohms impedance and 92 dB/w/m), but I think now the 105/2 would sound very real, really alive.
So I think an ECI-4 will be ideal, with 120 watts, and more than 80 A peak current, for a pair of Matrix 801. Anyway, if you could try it before buying, you can listening by yourself and buy (or not) with any doubt.
When I bought an ECI-3 integrated, I must go 11:00 o higher the pot, to real sound. With a Sansui amp (2x100w. RMS into 8 ohms) they sound very well.
Now, I have an ECI-4, but not the 105/2 (I sold it and get a pair of 104/2, with 4 ohms impedance and 92 dB/w/m), but I think now the 105/2 would sound very real, really alive.
So I think an ECI-4 will be ideal, with 120 watts, and more than 80 A peak current, for a pair of Matrix 801. Anyway, if you could try it before buying, you can listening by yourself and buy (or not) with any doubt.