balanced preamp

You might want to consider the Atma-Sphere MP-1 (2-box) or MP-3. Both can be ordered with a (absolutely sensational!) fully balanced differential 3-stage tube phonoamp. My amp is a McIntosh MC275 (tube) -- and since tube sound vs. ss sound is a function of the amp (and not the preamp, imo) your sonic result will be different.

I wouldn't make a selection using balanced as the most important factor to consider. I do feel its better but I would buy a component based on sound quality first. If it just happens to be balanced, thats OK too.

When I went to balanced connections with my ML 433 I was quite happy with the result. If a company goes to the trouble and expense of a fully balanced option, like your ML 336, it is likely to be the best option. But, just because a unit has XLR connections doesn't mean its fully balanced.

My ARC LS 27 and ML 433 sounded better even with cheap balanced cables than they did with expensive single ended.