I don't think there's one ultimate DOSBox config for all games.

GUS emulation with proper patch set will give you much better MIDI playback (if supported by the game) than what is called "Sound Blaster" in games.
GUS wavetable MIDI is similar in quality to Windows software wavetable MIDI emulation.

You won't hear a difference in wave sound between emulated GUS and emulated SB.

Sadly, what would give the best MIDI quality in most cases (AWE32 emulation with custom soundfonts) is not supported by DOSBox.

For the graphics part i heard there is custom DOSBox builds with d3d support. Should i install them?

You could try and play with the settings, yes. Just don't expect better in-game graphics just because of that 😀 But it may solve picture scaling problems (or cause them..) and compatibility problems with Direct Draw on some systems.

If there were an ultimate config, there wouldn't be a need for options to begin with 😉

Sorry i meant another thing. What i meant is prepare the config file to enable all sound and music support, install needed external patches. Then if a game support Gravis it uses it, if not then fallback to another good sound method coming after that. And if the second not supported fallback to the third. Is it possible to make it cascading like that?

The link below suggests various methods for using MIDI? Which one is the best? Or is it game spesific?
http://www.dosbox.com/wiki/MIDI_software_devices

Also is my Sound Blaster Z provide any advantage for me in?

It is too dependent on the game's themselves. Mostly you need to run the game's setup more than mess with DOSBox's conf. Some of it takes some knowledge of any given game. Such as the Sierra AGI games are best with Tandy sound, the earlier SCI games are best with Roland MT-32, SCI1.1 with GM and SCI32 used digital audio. Outside of Tandy, these need to be set in the games' setup, not DOSBox.

I tweak DOSBox on a game by game basis. IMO that is the ultimate config, unique to each game 😀

Perhaps grinninglich does not realize he can have a separate conf for each game.

I found answer to my question on the wiki:

"Most of the sound devices are capable of existing inside the same computer at the same time, so when configuring DOSBox sound you need to think of them as separate devices that can be enabled or disabled. Sound devices that are not in use do not use many resources, so you don't gain much in the way of performance by reducing the number of sound devices enabled. A game will likely only use a single device at a time anyway. (The one notable exception being routing music and sound effects through different devices, which was common for people with both a Sound Blaster and a separate MIDI device.) DOSBox also makes sure the appropriate environment variables are defined for each device, so game audio device auto-detection usually works, if the game attempts it. "

There is no absolute better sound variant, - it's subjective, depends on a game and quality of emulation. FM, GM or MT-32 - check all and decide. For DAC emulation GUS seems gives better sound.