Matched Tubes - Is there really a big difference??

Have a few Tung-Sol 6SN7 tubes but they are not matched pairs. I own a Counterpoint power amp modified to use two 6SN7 tubes. It is a hybrid power amp, tube ins with SS output. Will I hear a big difference if the tung-sols are not a matched pair? What exactly will I hear or be missing? The matched pairs go for $350-$400 ouch.

Thanks.