Oldest gear still for sale is . . .

Wasn't reel to reel around in the 40's. Ampex?
B

Tannoy has been around forever (since 1926). I don’t know what the oldest model is within their line that has a modern counterpart.
gdnrbob- my recollection is that "we" (the Allies) got tape technology from the Germans after WWII- the Magnecord,* I believe. Ampex was very early --not sure if it was the first US adaptation.
I was fortunate enough to hear the multi-tracks Les Paul cut to acetate--sort of direct to disc multi tracking- which I think was around 1948. (I checked quickly after I wrote this, and he had access to tape before that).
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*The German machine was actually called a "Magnetophon." I know Magnecord as a brand existed, but I wanted to correct the "record." :)

How about Wharfdale circa 1932? 
http://www.wharfedale.co.uk/product-list.php?cid=11

Oh, I thought you said "anything HiFi"...

I use some McIntosh MC 60s made in 1960, makes them 57 years. Use them every day. Terry Dewick is my friend.