Table wine" tweaking"

There is a winery in southern california…maybe the only one left.Besides selling grapes, fresh wine juice, they also ferment and make wine.
Last week, I went in to buy some used wine bottles and noticed that they had a few barrels of wine that were left over from other wine they had made. One rather large barrel was a mix of merlot, cabernet, Zinfandel, syrah. I gave it a taste it was quite passable. So I bought 6 gallons. It has been aging for about 1-2 months and I took it home. Now it has been 3 months.
Question?
I would like to add something to it to give it more flavor,body…you know.
I thought of adding some Oak to it, possibly some tannin or even pushing the envelope adding some other juices like a bit of blackberry or raspberry along with some sorbate and k-meta.

What do you think?? it is a nice table wine but I would like to add something to improve it.
It is still fining as I check for sediment.

advice?
Thanks,
Winebuff