These strings are a very good deal. I do not own a 7-string classical guitar. Rather, I bought these to experiment with lower tunings (ie B to b) on a standard classical guitar. With that in mind, I cannot comment on how they sound on the instrument for which they were intended.
On my guitar, the strings have a(n obviously) powerful low-end. Quite nice and resonant.
However, brilliance lacked with the lighter gauges; certain chord voicings sounded very "muddy." I can't blame this on the strings, alone, since I am using them on a slightly shorter scale length than what they are intended for. For the price, I cannot complain, and will surely order another set to have on-hand for future experimenting and inspiration.