preamplifiers

I'm seeking suggestions and advice on preamplifier purchase. I have A Soundcraftsmen Pe2217 preamplifier that I have hooked up to a ESS eclipse 500A amp and BGW 500D amp. I'm looking to change it to a Sony TAE 5450 preamp I could get for around 100 bucks. In your opinion(s) would this be a...

I have an Audio Research Ref 5 SE preamplifier and recently I have noticed an intermittent crackling noise from the speakers. The noise seems to be more on the right side. Are defective or old tubes the most likely cause. The tubes on this unit have got about 3,100 hours on them. Also, should...