100 watt to 160 watt solid-state or called 'brick' amplifiers are expensive new, so it makes sense to buy used. But, all are not equal in performance. I perform a lot of research and will not blindly buy anything. eHam reviews are a good resource for amplifier performance. So, what are the best amps and what should you avoid? Stay away from Mirage amplifiers. These are noted to have issues and failures. Most do not have a good high SWR protection circuit either. The best amps are made by TE systems & RF Concepts. The KLM are also good, but many lack the handy receive preamp. I recommend TE Systems and RF Concepts.