diff --git a/pyproject.toml b/pyproject.toml
index 12cc8fd..8a71aa5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,6 +37,7 @@ requires-python = ">=3.9"
 dependencies=[
     "PyWavelets",
     "colorlog",
+    "dbetto",
     "h5py>=3.2",
     "iminuit",
     "legend-pydataobj>=1.16.0",
diff --git a/src/dspeed/build_dsp.py b/src/dspeed/build_dsp.py
index 57af12d..04ba357 100644
--- a/src/dspeed/build_dsp.py
+++ b/src/dspeed/build_dsp.py
@@ -330,7 +330,9 @@ def build_dsp(
 
         # Get outputs from config if they weren't provided
         if outputs is None:
-            outputs = this_config["outputs"]
+            _outputs = this_config["outputs"]
+        else:
+            _outputs = outputs
 
         # resize inputs, get table and iterable versions
         if n_entries is None:
@@ -358,7 +360,7 @@ def build_dsp(
             processors,
             tb_in,
             db_dict=db_dict,
-            outputs=outputs,
+            outputs=_outputs,
             block_width=block_width,
         )
 
@@ -416,6 +418,7 @@ def build_dsp(
                     lh5_file=dsp_out,
                     wo_mode="o" if write_mode == "u" else "a",
                     write_start=i_start + i_entry,
+                    n_rows=len(tb_in),
                 )
             else:
                 tb_fill.append(tb_out)
diff --git a/src/dspeed/cli.py b/src/dspeed/cli.py
index b0e304d..8885671 100644
--- a/src/dspeed/cli.py
+++ b/src/dspeed/cli.py
@@ -6,6 +6,8 @@
 import os
 import sys
 
+from dbetto import Props
+
 from . import __version__, build_dsp, logging
 
 
@@ -55,6 +57,7 @@ def dspeed_cli():
     parser.add_argument(
         "--config",
         "-c",
+        nargs="*",
         required=True,
         help=""""JSON file holding configuration of signal processing
                  routines""",
@@ -172,11 +175,13 @@ def dspeed_cli():
             basename = basename.removesuffix("_raw")
             out_files.append(f"{basename}_dsp.lh5")
 
+    config = Props.read_from(args.config)
+
     for i in range(len(args.raw_lh5_file)):
         build_dsp(
             args.raw_lh5_file[i],
             out_files[i],
-            args.config,
+            config,
             lh5_tables=args.hdf5_groups,
             database=args.database,
             outputs=args.output_pars,