The name ACS Custom might not be the most well-known in today’s custom-fit in-ear monitor marketplace (that title probably belongs to Ultimate Ears), but the firm is certainly known by the company it keeps, with a client list that includes the BBC (BBC Orchestra, BBC Radio, and BBC Singers), Pink Floyd, Radiohead, U2, and many more. What’s significant, I think, is that many of these famous ACS Custom endorsers are known for creating music that is not only popular, but that places a premium on sound quality. To better serve its worldwide customers, ACS Custom maintains offices and in-ear monitor manufacturing facilities in multiple locations throughout Europe, the US, South Africa, Australia and New Zealand.
I had the opportunity to catch up with one of ACS’ principals, Dr. Craig Kasper, at the 2012 CES Show, where I learned about ACS. Much like the Chicago-based firm Sensaphonics, ACS believes strongly in building its in-ear monitors with earpieces made of soft-gel silicone materials, rather than the more commonly seen solid acrylic materials. As you’ll learn in this review, this particular design touch influences the performance capabilities of ACS monitors in several important ways, especially in terms of allowing an extremely comfortable fit with very high levels of noise isolation. I asked Dr. Kasper if he would recommend any particular ACS model for audiophile applications where a key objective would be to obtain the most neutral, accurate sound possible. Dr. Kasper recommended ACS’s T2 Classic Dual Driver model ($799), indicating that it was, at the time, the ACS model with the most accurate overall tonal balance.
The T2 Classic is, at least in terms of price, the middle model in the ACS lineup, positioned above the T3 Classic Single-Driver monitor ($479) and below the T1 Classic Triple-Driver monitor ($999). At first blush it might seem odd that the middle model in the range would be more accurate-sounding than the “flagship” model (at least in strict audiophile terms), but in fact this arrangement is pretty common in the world of custom-fit IEMs. What goes on is that top-tier IEMs are often designed more with the needs of performing musicians in mind, rather than targeted for customers who will use their IEMs primarily for listening to recorded music. Indeed IEMs designed for use as stage monitors often feature frequency response curves that deliberately incorporate certain strategically placed “colorations” with an eye toward helping musicians hear clearly even in the presence of extremely loud stage environments.