The brands you mention were very commonly available to US service personnel during the Vietnam war. I assume they were sold through the PX, but when I met people who had been over there, it was pretty usual that they had systems with those brands. Good? Well, a lot were big receivers, with over large bookshelf type speakers, the Garrards of the era were plasticy--by the standards of what I was running in say 1973--Phase Linear 700, Quintessence preamp, Technics SP 10 and stacked Advents, it was not quite the same. By 1975, I had gone to all ARC tube gear using the Quad Loudspeaker- the SP-10 stayed in the system for a long time. Kind of the difference between component separates and receiver based (or possibly integrated amp based) systems. 

I don't want to shun any of that gear- it was a snapshot in history- others may have a different view- I did not serve and I liked most of the guys who came back. I also felt for them because it was in the days before we recognized what the psychological impact was of being on the line. 

I remember this stuff well. Im sure this is what got me into this hobby. 

My sister was dating a guy ( she would marry ) that had recently returned from VietNam. The first time I saw his system I was blown away:  great big Sansui receiver, Sansui speakers with the intricate carved grill covers, Dual TT, big honking R2R and something you don’t see anymore that was more common then ; a reverb amp. This was around 1970. Ive been hooked ever since

I had a friend that was in Vietnam early. He purchased a couple pairs of large speakers and hid automatic weapons in them to ship home. It didn’t take long before the command staff found out. Fortunately for him and being a special position was able to get some good stuff. For him the stereo gear was long gone. To you vets , THANK YOU FOR YOUR SERVICE AND WELCOME HOME, YOU ARE LOVED AND APPRECIATED. Respectfully, Mike B. 

I just finished reading: The Vietnam War: An Intimate History by Ward and Burns. 

I was in college when the draft ended. What a cluster f*. Respect to the 58,000 that died, the over half million Americans that served and the million Vietnamese that died and many more that participated. What a cluster. 

While I lived through the time... I never really understood what was going on. With all the memoirs and declassified documents now available... this book lays it out starting at the beginning, one hundred years ago, and the war at all levels. 

I highly recommend the book.

The draft lottery continued for men born in my birth year 1955, and 1956 even though the active draft ended in June 1973.  My birth date was somewhere between 340 and 350.  So I, regardless of going to college, would not have been drafted during the Vietnam war.  I knew one person that served, and the experiences he conveyed of the stress, anxiety, and trauma endured were awful. I am not afraid to state that I question if I could have handled it.  All those who serve our country are special and deserve our most sincere thanks.  I contribute biannually to the Wounded Warriors Project.  
 

Regarding the equipment from the war era, and the brands mentioned,  I remember them well.  My father was sort of an audiophile at that time with his Pioneer SX 828, Large Advents, Thorens TD 161 and Stanton 681.  The music of the time was different IMHO.  It had either meaningful social commentary to stimulate change or songs of true love in the era of love.  Pop now has social commentary, but rather to stimulate change, it appears to try to only illicit reaction for the purpose and experience of that reaction. 

Someone recently posted asking for comments comparing your reference system to your retro system.  I still have a retro system in a VT vacation home (my dad’s Pioneer, DCM Time Windows 3, and a Linn Unidisc SC).  I responded as follows:  my retro system produces music that is warm and comforting like mom’s Sunday sausage and meatball tomato  gravy over spaghetti.   My reference system produces music with the fresh clarity to the pallet, and dynamic and vivid flavor profiles of the tasting menu at the Michelin Star Le Bernardin, NY.  

By 1973 the draft had effectively ended with only 649 men inducted. 
I turned 18 in 1972. In the high school lobby we kept a banner of the draft numbers updated daily. 
Maybe someone comment on the furniture made out of hashish that got shipped home. 
 

I have two cousins who served in Vietnam, who are twins. One in the Army, one in the Air Force. 
I don’t know what age I was at the time that they were home, but while attending a family party (possibly to celebrate their return) I sat in their bedroom listening to the stereo they had amassed and sent home. While Santana’s Abraxas played, I alternated between looking at the album cover and watching the reel to reel go round at that hypnotic speed that they do. I consider that afternoon as the beginning on my love of sound reproduction. 
We owe an incalculable debt to all veterans who served. Thank you from the bottom of our hearts. And, it would seem, I owe a little bit more to my cousins. 

I've listened to quite a few these vintage PX systems when they were new.

Most were either Sansui or Pioneer with large "Kabuki" speakers.

In 1971 I spent 3 months with a "quad" Sansui setup in Hawaii and it was a lot of fun after a few tokes of Green Afghan or an EarthTad of SillyCybin.

DeKay

My father in law gave me his old pair of PX-bought Coral BX-200 speakers. In bad shape and with corroded wiring. He had bought them when he was stationed over there. I rebuilt and refinished the cabinets and upgraded the caps. The drivers tested fine. I added new cloth behind the grills and they sound surprisingly good for 55-year-old speakers. He was happy that I can have them make music again. 

How did the guys with the massive stuff manage to ship it stateside?

I think the military contracted for cheap household goods shipments back to the States; I seem to recall that some servicemen brought sports cars back after WWII as well through a cut rate deal via the military.