Sugden amp to pair Harbeth SHL5? Not too thick?

HI,

I bought Harbeth SHL5, positioned it properly on filled skylan stands.

Now I drive it by DIY SET GM70 based tube amps, Audio Note tube PRE (M8), Linn Sneaky DS with modified Audio Note DAC 2.1x via SPDIF.

Sound is very refined.
I tried to use analog Linn Sneaky outputs, but it failed due to very average sound quality. AN DAC works much much better in all aspects.

Because Harbeth is a rather thick sounding speaker (I had before Audio Note E and Tannoy DC 15" drivers based horns), high frequencies are rather shy, I had to changes very civilized speaker cables from Audio Note silver litz (SP+SPe) to silver plated van den hul The WIND. WIND made speakers much more coherent , dynamic and a bit more open.

I wanted to simplify a bit my setup and make the sound more open. Tubes with Harbeth is a rather too thick sound combination. These speakers rather requires a lighter sounding setup and there is no need to warm sound with tubes or too relaxed cables.

AD rem:
I'm thinking about Sugden Masterclass IA-4 to combine power amp, pre-am and RIAA in one box. Tonality it should be similar to tubes (midrange quality)

IS Sugden warming up the sound a lot by working in A class?
Do you think, this is a good Harbeth match which gives well balanced sound with open and extend top-end?
Any advice, what would be the other good choice of integrated SS amp with good RIAA?

thanks