Is my Dynaco Stereo 400 worth repairing for resale?

@mswale 

Did you use fancy dancy caps and could you hear a big difference in the sound? If so, was it a good or bad difference?  I’m still trying to decide whether I want to keep the 400 or hopefully sell it.

Likely not very helpful, but I had a few Dyna 400s in my day, with and without meters. I found them to be ok sounding, but that was with analog only sources, different rooms and so on. I cannot speak for today if I would enjoy listening to one. I have a very large amp collection, and I enjoy many of them, as my speakers are very easy to drive. My best, MrD.

@curiousjim 

LOL, fancy caps. Well, I used audio caps (Nichicon Muse ES, Gold) for the signal path, and regular caps for everything else. Also replaced all carbon comp, and fuse resistors with metal film. 

Yes, it made a very noticeable improvement, everywhere! Bigger sound  stage, lower noise floor, cleaner sound, more bass, more high, cleaner mids, more dynamics. Like a vale was lifted. 

Also have a spare pre-power amp set as a backup, switched it back to back with refreshed vs original. The refreshed is just so much better. 

Like I said, cost was nominal, my time was vast. Think my pre-amp took 12 hours over a couple of days. Power amp was like 18 hours over a few days. Replaced over 100 parts (caps, resistors, diodes) in both units. 

IMHO your question really is a subjective one. I have a Dynakit Stereo 70 that my late Dad built in 1961.  My first experiences with audio were with a system that my Dad had in our Family den. The system was composed of a Fairchild 412 turntable with Shure tonearm and mm phono cartridge, Dynakit Pas 2 preamplifier, Dynakit Stereo 70 power amplifier and an Acoustic Research I speaker used as a subwoofer, with a Janzen electrostatic tweeter.  This was a really nice sounding system back in its day and I remember being introduced to many different genres of music through it.  The Holiday season was especially memorable listening to a myriad of different songs celebrating the Christmas Holidays.

So where many younger people might see a groady looking old tube amplifier, I see some wonderful memories from a long time ago.  

And at some point I am fairly certain that I will invest in having this old gem of an amplifier restored. 😊

I had a Dyna 400 that was a factory build, roughly 1973 as I recall. I got an accommodation since I worked part time in an audio store. I liked the idea of the "Dynaguard" (running from memory here), it performed well. I swapped it out for an original Phase Linear 700 which was a beast and yes, it did flame out, but got fixed promptly by Carver back in the day. (We are talking 1973 still). I used stacked Advents and went through my share of tweeters. Then did an about face, bought a pair of Quad Loudspeakers, built a Stereo 70 as a stop gap and within a few years, ARC preamp and amp. I've been in tube world since then.

I have no idea what it is worth today. Solid state stuff back then was not a smooth, it had a more pronounced "grain" in the mids- not specifically the Dynaco 400 but I remember the Phase Linear 400 sounding better than the 700 at the time. Whether it is worth a recap-- probably depends on how attached you are to it.

I still have my ARC Dual 75a-- which I kept for sentimental reasons. I recapped it in 2003 or so through an authorized facility and it was used intermittently as a rear channel home theater amp with two other ARC tube amps. I eventually got tired of the heat generated by all those tubes running in a home theater application and switched to a big McI solid state multi-channel basic power amp, which I still have. 

I don't know how many Dyna 400s are around or how that cuts in terms of market value should you want to sell it. We've come a long way in solid state since then though I'm still a tube devotee.