Inexpensive Tube Amps

It’s so easy for people to look down upon audiophiles that are new or have a minimal budget . In the price range you listed , avoid circuit boards . Also get something that uses common tubes that you can keep for a better amp when you move on . Get what you can adford and enjoy the learning experience . Someday when you move up/on, this will be the second system in your office . I had a Yamaha RV-X 1400, 105 wpc x 7. I changed it for an Anrique Aound Labs 30 wpc integrated. Had a really fun time . They were in the same price range and the 30 watt tube amp sounded better . If you can get to the $1k range , build a Bob Latino or buy a Will Vincent . You will love it , especially with upgraded driver tubes . New production power tubes are really quite good . Quicksilver is one of many quality affordable amps too . On the used market $1k will get you something that will have adequate power and decent sound quality . Interconnects , cords and tubes will be useful when you move on . As far as the sub $500 stuff , listen to the advise and don’t be afraid to return a couple . You fill find a synergy that will please you . And remember , like alcohol , drugs and women , tubes are highly addictive . Enjoy my friend , life is too short . Regards , Mike B. 

I recommend the McIntosh 275. 

In all seriousness though, I own the Musical Paradise MP-301 and love it. It is an absolute steal for the $$, especially if you upgrade the tubes. It is designed, supported, and shipped by an Asian guy who lives in Canada. It is manufactured in China. The guy has a day job so it is a hobby type of business. The amp is in its 3rd revision. 

Having read this thread and being a long time AG user, it seems a great lesson in the fact that there are many paths and many people in this hobby. Threads like tubes vs SS go on forever, but that is what makes it fun. My own personal preferences are for quality used stuff, just like I never buy a new car. But others go differently. For me the fun is in finding a good or even great piece of classic gear and upgrading it. Will it match my friend's Macintosh outfit? Of course not, but I can't afford that so I do the best I can. I think that is what the OP is after. 

Here's an old standby - Jolida. An old used one might be a good inexpensive investment. I've heard them make magic with Thiel 2-ways, low efficiency btw.
http://www.jolida.com/product/fusion-1102

Will, I can't speak directly to those amps you list but I do use one of those Chi-fi cheapies in my bedroom system, which is this one:

https://www.amazon.com/APPJ-mini2013-Original-miniwatt-Amplifier/dp/B00JSNLT28/ref=sr_1_fkmr0_2?s=el...

I might be made by Gemtune also.  It's only 3 watts and I use it with my 101db efficient Zu speakers.  I will say this, in a small room it sounds as good or better as any other amp I have owned, and that includes a few multi-thousand $$ amps.  I've been using it for about 3 years with no problems.  And if it breaks I will probably just buy another one for about $130.  

So if one of those you listed interests you, I say go for it. Only caveat is your speakers.  I did use mine to power some 88db B&W towers for a while.  It worked but the sound was nothing special. You might be ok on your 91db speakers but you'll have to try it and see.