I used this system in a professional environment for audio mastering and they resolve details in a recording that few other headphones can. The sound is precise but not fatiguing and you can truly lose yourself in the imaging and depth they convey. When originally released, the model SRX earspeakers were considered to be the finest available. When paired with the matching SRM-1/MK-2 driver unit, they become simply breathtaking! Ive recently upgraded to a newer set of Stax, which is the only reason Im selling them. The SRM-1/MK-2 Driver Unit has been recently been recapped using audio grade Nichicon KX and Elna Silmic II capacitors and the bias and balance were calibrated. Its a rare find to have both the earspeakers and the driver unit together.