The eAR 202 and 501 are lower cost alternatives to the eAR One and Two. The main reason they are less expensive is that they use ICEPower ASP-series modules, which contain an integrated switching power supply, unlike the A-series ICEPower modules (like those used in the eAR One and Two) which require an ancillary power supply. Another reason for the price disparity is that the ASP-series has built-in short circuit protection. The A-series does not, so Peter developed his own proprietary circuit, and the cost of this development effort is reflected in the eAR One/Two's higher price. I understand that Peter modifies his ICEPower modules for improved performance, but despite this he'd probably concede that the ASP-series modules still don't sound as sweet as the A-series based amps. I haven't heard the 202 or 501, but I admit that at their prices I'm tempted to try one of them in a second system.