I just received a gift of a model 1900 receiver and I see that it has 4ohm speaker output. Can I use my Zigmat Hornets 8ohm impedance speakers with this or should I look for a pair of 4ohm speakers.

Thanks 

No problem. The 1900 will deal with these happily. Speakers don't really have fixed impedances but vary across the frequency range. The lower the impedance, the more difficult they are to drive but the 1900 can deal with most perfectly well.

Thank you for the quick reply - looking forward to getting my Ziggies working. I am picking the 1900 up today from the repair shop - new caps and a couple of lamps.