Hadn't noticed the quad versus pair difference, but given that it's a transistor ladder, I'd be surprised if you need more than matched pairs.
Also, some people say that matching the capacitors used in transistor ladders is just as important. Haven't looked into it myself, but you might want to.
Also, some people say that matching the capacitors used in transistor ladders is just as important. Haven't looked into it myself, but you might want to.