AGA's 3.5 improves on what the Reference 3.1 brought to the table.  According to the company, the musical capabilities of the 3.1 have been expanded by a wide margin.  

"In creating the Reference 3.5," says AGA VP William Fried, "we married key elements of the Reference 3.1 with new innovations found in the Strada, added OPT® Level 2, and the result is an engineering masterpiece that connects the listener with their entertainment on entirely new levels."

In addition to S2 technology, which enhances low frequencies, AGA has introduced a new CDT 3 tweeter, which uses a new grill topology that uses a new grill topology designed to improve vertical dispersion.