These are not exactly comparable cartridges... and I don't know if you're looking for something specific?
I would find the Allaerts the most musically precise (tonal accuracy, relative dynamics, good extension maybe a tad on the light side).
To coin a phrase (or two): The Koetsu has the unique ability to pick up what it can give you beautifully and disregards the rest. Hence, you don't bother about that rest.
I haven't heard the Sumiko in familiar surroundings.
Cheers
I would find the Allaerts the most musically precise (tonal accuracy, relative dynamics, good extension maybe a tad on the light side).
To coin a phrase (or two): The Koetsu has the unique ability to pick up what it can give you beautifully and disregards the rest. Hence, you don't bother about that rest.
I haven't heard the Sumiko in familiar surroundings.
Cheers