pop and click filters

Yes such devices have been manufactured. Back in the 1970s a company named Burwen put out two units, one for tape hiss, and one for clicks and pops. In the 1980s and 1990s a company named Packburn in Dewitt, NY (near Syracuse) put out the Packburn Audio Noise Suppressor Model 323A, which had a stage for diminishing hiss as well as a stage for diminishing clicks and pops. For a while it was listed in Stereophile's "Recommended Components." Stereophile called the Packburn "the Cadillac of nose suppression units." I ended up getting one directly from the company for $2,400. As the years have passed, it has developed a hum. Whether the hum is an internal issues, or whether there is an externl factor, I don't know. I haven't try to deal with it seriously because I now transfer my LPs to CDs using Sony's Sonic Forge software.

SAE offered the Impulse Noise Reduction System. There are two currently ending soon on EBay, one model 5000 and a 5000A.

I went to Google and typed "Packburn." There are quite a few sites dealing with noise reduction devices. Might be worth some of your time.

Thanks to all of you for your help. I will follow up on all your suggestions.

At one point or other I tried all of the above with the exception of the Packburn, and found they all simply did more harm than good. I would think that now something much better would be possible in purely digital foremat, but have no idea if anything is.