The HD in HD Radio© means nothing specific...it's just the copyrighted name of that technology. It probably is intended to make buyers feel that the quality improvement is equal to high def TV.
I'd suggest trying the Sangean HDT-1X from a seller like Crutchfield with a liberal 30 day return policy. The HDT-1X has a digital output that is said to sound good through a good DAC; the HDT-1 is the earlier version lacking the digital output and a few other enhancements. I'm planning on trying the HDT-1X through my TADAC, but my location might be too remote for a clear signal.
I'd suggest trying the Sangean HDT-1X from a seller like Crutchfield with a liberal 30 day return policy. The HDT-1X has a digital output that is said to sound good through a good DAC; the HDT-1 is the earlier version lacking the digital output and a few other enhancements. I'm planning on trying the HDT-1X through my TADAC, but my location might be too remote for a clear signal.