You have to look at it that [(bass guitar + amp) + effects] = your sound.
The is very true. The amp and speaker really should be considered an extension of the instrument, and IMHO the speaker and type of strings are often the parts that makes the biggest difference in sound.
My sad little story. I had to have to best amp when I was getting started. I played what was available in the local area. There were three nice choices with 215 cabs that would have served me really wel. I could have chosen between 215 rigs made by Sunn, Yamaha, and Fender.
After doing a bunch of reading I fell into the hype surrounding the Ampeg SVT and 810 being the king of bass amps. All the articles were filled with swirling superlatives the created the perception the amp would sound fabulous from the top to the bottom of it's frequency response. I had one special ordered on layaway and began paying it off, even though I had never heard or seen one. Surely it would be awesome because everyone said it was the best bass amp ever made.
The amp came in after I had payed it about half way off. The store let me play it on the show room floor and I thought it sounded horrible. I also suspected that it might be some sort of fake because this was around the time when MTI had taken over, so it looked a little different than all of the photos I had seen. No getting out of a special order so I payed it off and took it home.
Over the years I have learned that I actually like SVTs but I the sound of Ampeg 810s is not my cup of tea. I currently own a 69 and an 87 SVT. I eventually sold the MTI rig in near mint condition for about 1/3 of what I payed for it, and it took about a year sitting in a music shop.
If it were not for the current health threat, I would tell you to go play as many amps and cabs as you can, before you buy. Don't limit yourself to amps and cabs from the same manufacturer because amp/cab pairings can be a critical element in getting a certain sound, and sometimes you get a special synergy by mixing and matching. Some amps play well with most speakers, and some don't. Likewise some speakers play well with most amps, and some don't. Some combinations are down right awful, so it's a really good idea to try before you buy.
Don't let my experience put you off trying an Ampeg 810. Lot's of people still swear by the sound of P-bass, SVT, and 810. I played a Ric 4001 when I bought mine, and I was going for a HiFi tone a few years before it become common. Not the right rig for my goals.