Modern feminism puts a lot of emphasis on intersectionality, so it does take into account class (as well as race). As for which kind of inequality is more "fundamental", it doesn't matter much in practical terms.
It does matter, because you the subjugation of women is predicated on the division of human beings into classes. Without class society, you wouldn't have male chauvinism and the subjugation and super-exploitation of women.
Also, intersectionality is fundamentally incorrect in that it proceeds from a standpoint that social class is an oppressed 'identity' much like that of women or blacks or [insert identity here]. While there is certainly class prejudice (and I would obviously not deny this, having been on occasion referred to as 'trailer trash,' 'white trash', etc.), working class people are not discriminated against in the same way as blacks or women (i.e. because of their class position), and thus that does not define how the working class as a social category comes into being or exists (in opposition to the other classes in society). The entire identity as such is predicated on the relationship of the person in question to production, the necessary ingredient for figuring out where one stands in the class society in which he or she resides.
Class is based on labour and wealth, with labour and wealth being based on power (exercising power or exerting labour through physical attributes) Power flows from the powerful which if you wind it right the way back biologically has been male. Man's power over women on the basis that men are physically stronger, penetrate women and are not subject to pregnancy or other reproductive 'constraints' pre-exists the collectivisation of any one or any thing. It pre-exists communities and any forms of socialisation rooted as it is in our genetic inheritance as mammals.
Isn't basing response on class not in fact, 'usurping' the role that sex/gender has had in establishing these power structures?