I use one myself and I find it useful when using a receiver without a great
sync detector. however I have an extra one

the SP-200 has in one box an
audio amp and
speaker
controls for:
bass
treble
audio peak
audio notch
noise limiter
squelch
tape controller

it is better than the alpha delta VRC in my opinion

the SP-200 cost $200 when new and Grove doesn't sell it anymore

I will sell my extra one for $85 which is basically what I paid for it. add
a bit for shipping

the SP-200 is on my radio bench and will be featured in my revised web page
coming in October.