Upgrading to 9.4h is entirely up to you. If you want the features 9.4h has, then go for it. Otherwise, leave as-is. Personally, I wouldn't run / play any TZ without 9.4h. (Unless you plan on operating it on location.. Then use 9.2)

For the sound - define 'weak'? Quiet, or sounds like it has too much treble or bass?

Or 9.4ch

LTG : )™

At least with the Home Rom, you can empty all balls with one command instead of having to go through the gumball machine every time.

I remember 9.4h may have the pause feature, but that may be a later ROM (or was 9.4h the latest released?)

NO. Do NOT use 9.4ch. For f*cks sake, you of all people should know how angry that made Ted, and if that hadn't happened, we'd very possibly be on 9.9h by now.

9.4H is the latest, and yes, it has the 'mute and pause' feature. (Though.. make sure your flipper coils are in good condition, and don't leave it on too long. Hate seeing burnt out coils..!

Stuff added in 9.4h.. It's long:

Version 9.4H
Date: February 28, 1995
U6: Checksum: C494

Changes from revision 9.4:

NOTE: The "H" (home) ROM is "free play only". It will not take
money to do pay for play.

1) Added a new adjustment: "LITZ CHEAT OK". When set to
YES, this allows the player to hold in the buy-in
button during game play to enable Lost in the Zone.
The next shot to the Slot Machine or Piano will
start a LITZ "practice round". The player is not
able to enter intials for LITZ champ if the cheat has
been performed.

2) Implemented "Mute & Pause" mode. Pressing buy-in Button
while holding a flipper will kill music and keep flipper held.
Pressing buy-in again will resume regular play.
This feature can be disabled by adjustment ("MUTE & PAUSE OK").
The game resumes automatically after 15 minutes.

NOTE: If you are worried about your flipper hold coil getting
hot with this feature, then disable it.

3) Added a magnet ball-catching effect at the beginning of multball.
This will catch the balls on the magnets if all of these conditions
are in effect:
- 3 magnets installed, and all 3 work
- adjustment for the effect is ON
- 0 or 1 balls in the lockup
- white ball is in the gumball machine
(Note that the last condition requires that the game
has actually seen a white ball loaded since last
power up or exit from Test mode, since the location of the
white ball is not tracked across initialization.)
This effect can be disabled by adjustment ("MB ST. 3 MAG. GRAB").

4) Added an adjustment that allows white ball detection during multiball
("M.B. P.B. DETECT OK"). With this adjustment turned ON (default)
the game behaves as before. With it OFF, then the game can no longer
be fooled into thinking the white ball is in play by a quick 1-2 shot into the
piano and slot machine. Use of this adjustment is recommended only
if all of the proximity sensors are correctly functioning.

5) Added a preset ("INSTALL #pinball") for home adjustments
desired by group of silly Twilight Zone owners.

Version 9.4

Changes from revision 9.2:

1) Fixed a Powerball/Multiball bug where the Powerball
was not detected when it was the 2nd ball served
from the trough for Multiball start.

2) Fixed Super Skill Shot bug where a completely missed
shot would end the ball and give Super Skill Shot to
the next player up.

3) Added ball search to the ball recycling at the end of
Lost in the Zone.

4) Enhanced the ball-type detection logic on the magnets.

5) Fixed a bug with Bonus X lamp after Bonus X awarded.

6) Added/enhanced a few lamp effects.

7) Improved the grace period logic at the end of Battle
the Power timeout.

8 ) Added a grace period timer for the end of multiball
that indicates the Powerball was in play. This enables
Powerball jackpots during the jackpot grace period.

9) Added code in attract mode to page through the amode
pages by using a flipper button.

10) Added the player-selected tournament module.

11) Added some stuck switch logic detection at power up.

12) Improved/fixed logic for games with the 3rd spiral
magnet installed.

13) Fixed a bug at MB start where two balls get stacked on the
autofire kicker.

14) Fixed a lamp update problem when going from 'unknown'
ball state into 'steel' ball state after a lock.

15) Fixed a bug in Clock Chaos where it would speed up the
mechanical clock, even though another mode was using it.

16) Turned off the mini playfield magnet search pulsing if
'battle the power' gets restarted before the search from a
previous battle. Same goes for battling during PB mania.

17) Spruced up custom message a bit to use a fatter font
if it fits on the screen.

18) Added a new setting for Spiral Extra Ball Memory.
The new setting "BY SPIRAL" makes the EB track the
carry-over setting of the current spiral set.
That is, the EB carries over if the sprirals carry over.

19) Made the lockup kickout wait until LITZ intro is done.

20) Fixed a sound bug when adding credits during game play.

21) Added an "Empty Balls" test.

22) Added a separate high score to date table for players
who bought in 1 or more times.

And because I see the question often - 9.4 (non-H) was never released. It was originally GOING to be released as an 'official' firmware, until WMS told Ted to stop working on it. So that code was committed to the software repository as a potential release, and then when WMS said no more, he started working on home-only stuff, 9.4H.

Yes I do know. And I am sorry it happened.

Unfortunately it is out there. And downloadable from the IPDB.

LTG : )™

May I ask what is 9.4ch? Never heard of it.

Hacked version of 9.4H that takes monies.