I think the Heresys will definitely be an upgrade over your Cerwin Vegas. They will not dig the deepest(around 50Hz with boundary gain) but the bass they do produce is tight and punchy and fast especially with your Acurus A250. The bass drive with that amp is remarkable especially for it's price point. My A250 drove my Heresys really well in my 13W x 13L x 10H spare bedroom. I am not using a subwoofer with mine but a quality sealed subwoofer will add that extra deepness you may want. Same applies for my Heresy II's in my master bedroom
Bill
Bill