Classic Audio give the common resale value on some gear. 
http://www.classic-audio.com/

Most of the stuff shown in the Classic Audio marketplace is
 just open auctions that are from elsewhere. Therefore, I use:
 
Ebay.
Run a search for the item you are interested in.
Search both open and closed auctions.
This serves as a real world barometer as to what these items
are actually selling for and their popularity in the used market.
Armed with that info, you will know what a "good deal" is
if you happen to find the same item locally at a garage sale or swap meet
or at a Goodwill outlet as well as Craigslist.
 
Here again, buyer beware. Old stuff can be in bad shape requiring
expensive rework or repair.

 
Quote:

skylab said:

For $50, this is silly-good sound from a headphone amp.

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Hee hee. What'd I tell ya? And your Kenwood is from the early '70s. Wait'll you hear some stuff from late in the decade or beyond, when everyone decided to tackle the "transistor sound" problem.

Quote:

wualta said:

 
Hee hee. What'd I tell ya? And your Kenwood is from the early '70s. Wait'll you hear some stuff from late in the decade or beyond, when everyone decided to tackle the "transistor sound" problem.

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Haha, that's true too, there are so many nice sounding SS stuff in the late 70s.  Early 80s had some decent stuff too.  Skylab or anyone, if you ever see any Optonica gear for sale and cheap too I would recommend you pick them up.  They were Sharp's high end equipment and were really advance back the day but they had lousy marketing so it never took off, but they made excellent stuff.  Some of their turntables used a granite (real) plinth, and the table probably weight near or over 30lbs from what I've read.

Well the Marantz 2275 I just bought will be the more interesting test. While still not expensive by the standard of the sort of headphone amps we buy around these parts, I paid several hundred dollars for a mint unit, which is a lot more than the $50 I paid for the Kenwood. So the Marantz will face a bit more scrutiny, not just from my headphone amps, but also from my vintage Fisher KX100. Will be a fun time comparing them. This is my latest little "project"

Quote:

skylab said:

Well the Marantz 2275 I just bought will be the more interesting test. While still not expensive by the standard of the sort of headphone amps we buy around these parts, I paid several hundred dollars for a mint unit, which is a lot more than the $50 I paid for the Kenwood. So the Marantz will face a bit more scrutiny, not just from my headphone amps, but also from my vintage Fisher KX100. Will be a fun time comparing them. This is my latest little "project"

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Marantz generally sell a lot higher than other brand names because of the history being an American company, however the Japanese did purchase the company in the early 70s.  But, being made in USA and being an Americana item makes it valuable to some, generally Americans.  JBL is another.  I'm the same way with Canadian products, if I can find any haha.  From what I know of Marantz, and I've only heard them never owned, they sound really smooth very comparable to tubes but with more oomphs, Good mid range and bass and also good treble, however it may not be as "sharp" compared to other SS amplifiers.  I think your receiver is 75wpc?  I think this unit generally sells between 200-400 depending on condition.  Worth while for some and others might look else where.  Desirability, especially in vintage, doesn't necessarily reflect on the sound quality or features they produce but rather affected by the people who are looking for them and what they're willing to pay.  Anyone have interest in vintage speakers?

searching ebay I see some vintage receivers have been cleaned and serviced and many are flaunting the fact they have "original transistors" and "new LED lighting" for the panels.  Is this a good thing?  I mean the original transistors vs. new transistors.  And aren't those LEDs brighter than the original soft glow of the original Marantz look??

Quote:

tnmike1 said:

searching ebay I see some vintage receivers have been cleaned and serviced and many are flaunting the fact they have "original transistors" and "new LED lighting" for the panels.  Is this a good thing?  I mean the original transistors vs. new transistors.  And aren't those LEDs brighter than the original soft glow of the original Marantz look??

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Well, newer transistors can change the sound quality so being original is better but it's just how they want to "market" their ad.  But, transistors can last for quite some times unless it amplifier was abused or wasn't properly cared for.  Bulbs die out and need to be replaced and don't affect the value at all.  Some bulbs are unobtainable and need to be replaced with LEDs.

I wouldn't want "new transistors", but LED bulbs are a godsend. Replacing lightbulbs sucks. I had a Dynaco Stereo 400 with the coolest blue meters, but that thing ate through lightbulbs like a teenager eats big macs.

if "old" transistors are replaced with "newer" or recent equivalent transistors and the sound is worse, then most probably the bias servo circuit
is out of whack and needs adjustments. if it has the adjustable bias servo it can be adjusted to account for the differing characteristics of the
transistors. the performance headroom of the amp bias servo circuit needs to be restored for the amp to sound as it was intended. and imo,
transistors, although they do contribute, do not make the sound of the amp, on their own. the design and topology is the more critical factor imo.
 
this applies as well to the caps. changing out caps requires adjustments to the bias servo as well. transistors and ic's usually last many decades
if used within their tolerances, but eletrolytic caps do not last forever. those found in the power supply section are usually the culprit; as they
lose their ability to hold the voltages, thanks to the eletrolytes drying out over time, the current getting through increases and tends to fry
the resistors, transistors, ics, relays and others...

many thanks to you all for educating me on the transistor issue. And LEDs vs. original lighting sounds logical too

Here is my Sansui 9090db, it sounds quite good with my HD650's.  I will be building a bottlehead crack amp soon to see how a dedicated headphone amp compares.
 

 
I also have a pair of EPI A120's that are in desperate need of a re-foam. The tweeters in these are one of my favorites.  Very good detail with-out listening fatigue.
 

 
This is my Rotel RX-403.  It definitely doesn't sound as good as my Sansui, but I picked it up for 50 cents at a garage sale and it got me through high school and college.
 

I will have to post up a picture of some of my other gear.

If no one's mentioned it yet, Audiokarma.org is a whole gaggle of forums devoted heavily but not exclusively to vintage electronics, tape machines, speakers, and what have you. What doesn't satisfy them, they modify. Not unlike HF, come to think of it.
 
Yeah, don't pay too much attention to the "original transistors" ploy-- kinda makes you wonder what else might have been swapped out. Mostly you want to know if a given piece has been serviced, and if so, what was serviced, and by whom. Sometimes replacement parts have to be hand selected so they match existing parts, so you want the work to have been done by someone competent. So always ask the "has it been serviced" question. Sometimes the seller knows, and sometimes not. If not, you have to do some detective work and get photos of the interior, and so on. Buying vintage is fun and cost effective, but it's also a gamble.
 
And yes, Optonica is worth a second look if you stumble over some. They made a very interesting MOSFET power amp, for example.

I am a new vintage receiver owner!!  Picked this up today.  Haven't had a chance to listen yet.  I idiotically left my headphones at the shop haha.  Picking them up tomorrow.