Don, I wouldn't think that the 8 ohm speaker would be that much of a mismatch, but my old Drake headphones have a 100 ohm, 1/2 watt resistor in series with the "hot" lead. You might try that on yours (Drake hides it in the phone plug) and see if the hiss goes away on the phones. Good luck. You'll like the R4B when she's right! 73, Don, WB5HAK